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C1, FM 6-2
Change 1
HEADQUARTERS
DEPARTMENT OF THE ARMY
Washington, DC, 16 October 1996
Tactics, Techniques, and Procedures for
FIELD ARTILLERY SURVEY
FM 6-2, 23 September 1993, is changed as follows:
1. New or changed material is indicated by a star
2. Remove old pages and insert new pages as indicated below.
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8-13
8-13 through 8-16
9-3 through 9-5
9-3 through 9-5
10-1 through 10-7
10-1 through 10-37
13-1 and 13-2
13-1 through 13-4
14-1 through 14-22
14-1 through 14-23
B-1 and B-2
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C-1 and C-2
C-1 and C-2
D-1
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E-1 through E-9
E-1 through E-38
H-1 through H-5
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Glossary-1 through -8
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Index-1 through -10
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DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited.
By Order of the Secretary of the Army:
DENNIS J. REIMER
General, United States Army
Chief of Staff
Official:
Administrative Assistant to the
Secretary of the Army
02469
DISTRIBUTION:
Active Army, Army National Guard, and U.S. Army Reserve: To be distributed in
accordance with the initial distribution number 110765, requirements for FM 6-2.
C1, FM 6-2
PREFACE
This publications is a guide for commanders, survey officers, and all personnel whose duties
include planning, supervising, and performing field artillery (FA) surveys or training in those
areas. The material presented herein applies without modification to both nuclear and nonnuclear
warfare. This manual provides—
Doctrine for instruction and employment of survey sections.
Guidance and reference in survey principles.
Procedures used in operating and maintaining equipment.
This manual discusses the survey personnel and equipment available to FA units. It describes
and discusses—
Measurement of angles and distances.
Techniques of recording field data as they are determined.
Different methods used to extend survey control.
Basic astronomy and the methods and techniques used in astronomic observation to determine
direction.
Determination of relative locations on a rectangular grid system by using conventional
survey methods, the position and azimuth determining system (PADS), and the global
positioning system (GPS).
Survey requirements and techniques used for different FA weapon and fire support systems.
Survey planning required at all echelons.
Standardized procedures relevant to survey operations (Appendix A) (denoted in text by
a large asterisk [*]).
Survey standards and specifications (Appendix B).
Training for the FA surveyor (Appendix C).
Locally reproducible forms for use with the backup computer system (BUCS), the forward
entry device meteorological/survey (FED MSR), and for recording survey control point
(SCP) data. (See Appendix D for a list of these forms and the back of this publication
for copies of the reproducible forms.)
It also includes the ellipsoid and datum tables (Appendix E), a grid zone chart (Appendix F),
star cards (Appendix G), and extracts from the standardization agreements (STANAGs) and
quadripartite standardization agreement (QSTAG) implemented by this book (Appendix H).
This publication implements the following international agreements:
STANAG 2934, Artillery Procedures--AArtyP-1. (This STANAG combines STANAGs
2865 and 2373.)
QSTAG 269, Survey Accuracy Requirements for Surface-to-surface Artillery.
The proponent of this publication is HQ TRADOC. Send comments and recommendations on
DA Form 2028 (Recommended Changes to Publications and Blank Forms) directly to the following:
xiii
C1, FM 6-2
Commandant
US Army Field Artillery School
ATTN: ATSF-GCS
Fort Sill, OK 73503-5600
DSN 639-6616/2805
Commercial (405) 442-616/2805
Unless this publication states otherwise, masculine nouns and pronouns do not refer
exclusively to men.
xiv
C1, FM 6-2
CHAPTER 1
MISSION, RESPONSIBILITIES, AND DUTIES
The mission of FA survey is to provide a common grid that will permit the massing
of fires, delivery of surprise observed fires, delivery of effective unobserved fires, and
transmission of target data from one unit to another to aggressively neutralize or
destroy enemy targets. The establishment of a common grid, and the single
operational datum within the common grid is a command responsibility.
NOTE: Common grid refers to all firing and
target-locating elements within a unified command
located and oriented, to prescribed accuracies, with
respect to a single three-dimensional datum.
1-1. SURVEY PLANNING
a. Field artillery survey must provide indirect fire assets
and target-locating assets with a common grid. Common
survey control allows the maneuver commander to employ
fire support resources with a guarantee of accurate and timely
fire support. Survey planning within the force is based on
the following tactical considerations:
The commander’s target adjustment policy (that is, if
the element of surprise is an important aspect of his
tactical plan).
The requirement for transfer of adjusted target locations
to higher and lower echelons.
The required attack of deep high-payoff targets onto
which fire cannot be adjusted (or if surprise is a factor).
The planned positioning of indirect fire units during
each phase of the operation.
The planned tasking of target acquisition (TA) sensors
and the processing of targets to an attack system.
b. The maneuver headquarters (HQ) establishes survey time
lines and accuracy requirements in the initial planning stages
of an operation. The maneuver commander gives the artillery
commander (fire support coordinator [FSCOORD]) targeting
priorities and the effects he requires on high-payoff targets.
This information translates into survey requirements for the
TA sensors and the designated attack systems, which must
be on a common grid by the time required. The effects
required on the target and inherent system inaccuracies
determine the survey accuracy requirement (hasty, fourth-order,
or fifth-order survey).
1-2. SURVEY OPERATIONS IN
THE AIRLAND BATTLE
AirLand Battle (ALB) doctrine describes the Army’s
approach to generating and applying combat power at the
operational and tactical levels. Surveyors must adapt this
doctrine to their mission.
a. AirLand Battle Surveyor. The ALB surveyor
understands the principles of all survey methods. His attitude
is that some kind of survey is always possible, and some
survey is better than no survey at all. He is a thinker
with an open mind, an expert in land navigation, and
confident in himself and his leaders. He takes the initiative
to ensure a successful survey mission. Using initiative
and ability, he makes good use of the available time and
resources to provide accurate survey control when and
where it is needed.
b. Survey Mission Under AirLand Battle. The mission
of FA survey-provide a common grid—does not change
under ALB doctrine. However, the use of split battery
operations, composite units, intelligence and electronic
warfare (IEW) sensors, new systems, and greater dispersion
and displacements have increased the survey workload.
During the first 2 or 3 days of battle, artillery units expect
to make many moves. The number of survey points required
will depend on the type of unit and the intensity of battle.
Prior planning is essential. Before hostilities begin, units
should survey a network of artillery positions in their
area of operation.
c. AirLand Battle Basic Tenants. The ALB basic tenets
of initiative, depth, agility, and synchronization are the
foundation of the Army operational concept. Survey leaders
and planners must understand how the ALB basic tenets
relate to the survey mission.
(1) Initiative equates to the importance of speed. It means
making things happen more quickly than the enemy can
respond. Early planning enables commanders to take the
initiative by ensuring that acquisition and firing units are
located by common reference in relation to each other and
that the data are timely and to the required accuracy. This
provides for the rapid transfer of target data to and between
firing elements without degrading accuracy.
(2) Depth is important to the survey planner. It directly
relates to the need for accurate and responsive common survey
control for deep strikes against the enemy and for accurate
fire support in close and rear operations. A combination
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C1, FM 6-2
of PADS and conventional methods provides the flexibility
needed to ensure precise and rapidly extended common survey
control to fire support elements (FSEs) in support of the
maneuver forces.
(3) Agility is gained through flexible organizations and
quick-minded, flexible leaders. For FA survey, agility means
having an appropriate mix of equipment and personnel
capable of adapting to changing conditions and responsive
to leaders who can “think on their feet.” The ability to
use conventional methods when and where they are
advantageous gives the survey section added agility.
(4) Synchronization refers to unity of effort throughout
the force. Common survey control ensures this unity at every
echelon in the fire support chain when required. Survey
planning and cooridnation are, therefore, part of
synchronization.
d. Command and Control. Command and control is an
important part of ALB doctrine. Planning, communications,
and coordination are essential parts of command and control.
(Chapter 14, Figure 14-13 outlines the communications
network for FA survey.) Field artillery survey planning and
coordination begins at the corps artillery survey planning
and coordination element (SPCE) with an interface between
the topographic (topo) engineers and the SPCE at division
artillery (div arty) and FA brigades. Communications is
the key to the up, down, and lateral flow of information.
The div arty survey officer and FA brigade chief surveyor
further coordinate the survey plan down to battalion level
with the battalion reconnaissance and survey officer (RSO)
and chief surveyor. This type of command and control
ensures a successful survey mission.
1-3. FUNDAMENTAL SURVEY
OPERATIONS
Successful accomplishment of the mission depends on the
fundamental survey operations in Table 1-1.
a. Planning. Survey planning begins with understanding
the maneuver commander’s intent and receiving the
FSCOORD’s guidance. Then a thorough map and ground
reconnaissance (recon) is conducted. When the PADS is
used, ground reconnaissance and survey operations are
conducted concurrently. During planning, full consideration
is given to the following:
Terrain.
Weather.
Personnel.
Time available.
The commander is responsible for establishing a common
grid and, therefore, accomplishing the survey mission.
However, survey leaders must keep the commander informed.
When the survey plan cannot support the commander’s
guidance, survey planners must pass the plan to the S3 and
the commander. They will review, adjust, and/or approve
the plan. Aggressive survey planning that answers who,
where, when, why, and how is absolutely essential to ensure
mission success.
b. Coordination. Coordination and planning originate at
the corps SPCE located at the tactical operations center
(TOC). The corps SPCE is the interface between the topo
engineers, division artilleries, and nondivisional units
requiring survey control. This coordination and planning
effort at div arty is accomplished by the survey officer
assigned to div arty headquarters and headquarters battery
(HHB). The division survey plan is further coordinated at
the battalion level with the battalion RSO. Interface between
all echelons of command must be maintained to ensure that
common survey control can be provided to units in support
of maneuver commanders where and when it is needed. The
coordination and synchronization of the survey plan are
essential to mission success.
c. Fieldwork. Survey fieldwork is performed by the survey
personnel to extend common survey control throughout the
area of operations. Fieldwork includes establishing SCPs,
measuring distances and horizontal and verticaI angles,
making astronomic observations, and accurately recording
field data and sketches of SCPs established. The fieldwork
must be started immediately on receipt of the commander’s
orders and be continuously and aggressively pursued until
completion of the survey plan.
Artillery commander’s concept.
d. Computations. Survey computations include the use of
known data to initiate PADS or conventional operations and
the conversion of appropriate elements of field data to usable
horizontal and vertical position locations and azimuths.
Survey computations and fieldwork are performed at the
same time.
Priorities.
1-4. PLANNING RESPONSIBILITIES
Tactical situation.
a. Each FSCOORD is responsible for ensuring that required
survey control, consisting of both horizontal and vertical
position location and an orienting line of known direction,
is furnished to subordinate units by the time required and
Operational datum and survey control available.
Desired accuracy.
1-2
Number of installations.
FM 6-2
to the required accuracy. The FSCOORD must issue orders
to the S3 and/or survey officer so that detailed planning
and coordiantion may begin. The FSCOORD guidance must
provide priorities; accuracies; time to be finished; primary,
alternate, and supplementary position requirements; and
future plans.
b. The S3 is responsible for the direct supervision of the
survey officer. The S3 issues orders and provides guidance
based on the FSCOORD’s requirements. The S3 coordinates
with higher- and lower-echelon staff officers and
commanders and advises the commander on any deviations
from previous orders.
c. Survey operations must be started as soon as the
requirement for survey has been identified. The goal is to
establish survey control before occupation by the firing or
acquisition elements. All training should point toward this
end. The FSCOORD is responsible to coordinate the
movement of survey teams with the maneuver commander.
Table 1-1. Fundamental survey operations
ACTIONS
OPERATIONS
Planning
Receive artillery commander’s guidance.
Conduct map end ground reconnaissance.
Formulate survey plan, end issue orders detailing the following:
• Accuracies.
• Time to finish.
• PADS requirements.
• Alternate plan.
Coordination
• Priorities.
• Logistics.
Ž Conventional requirements.
Ž Future requirements.
Ensure communications requirements are met and survey data are available where and when
needed to include the following:
Ž Higher headquarters.
• Adjacent headquarters.
• Survey information.
• S2 and/or S3.
• Commanders.
Ž Lower headquarters.
Fieldwork
Establish and mark survey control points.
Provide PADS update points.
Provide update points for stabilization reference package/position-determining system (SRP/PDS).
Establish position and azimuth for all FA systems requiring survey control.
Measure distances and angles.
Make astronomic observations.
Record and sketch field data.
Supervise and/or synchronize PADS-conventional survey interface.
Computations
Compute direction.
Compute horizontal and vertical location.
Convert to common control.
Transform data between grid zones and datums.
1-3
FM 6-2
d. When survey control is not immediately available, all
efforts should be directed toward establishing common
directional control in the position area. Recommended
methods of establishing direction by priority are as follows:
• Astronomic observation.
• Simultaneous observation with direction established
• the master station by–
– Astronomic observation (sun or star).
– Survey instrument, azimuth gyro, lightweight
(SIAGL).
– PADS.
• Directional traverse by using a theodolite.
e. Providing the best available direction and location may
take precedence over accuracy of data. In some situations,
the commander may have to accept survey accuracies that
fall short of the specifications given. This determination is
the commander’s decision. Survey leaders must advise the
commander of the effect of inaccuracies on the guarantee
of fire support. For example, in a conventional survey in
which the azimuth closure error is excessive, the ability of
a fire support unit to accomplish a tire mission on schedule
may depend on using the best available data and may require
time for adjustment. The use of substandard survey data
can affect hitting the target and also could result in friendly
casualties. However, these surveys of degraded accuracy
should be rerun when the tactical situation and time permit.
f. If the terrain or the tactical situation is such that the survey
sections of div arty, HHB, target acquisition battery (TAB),
and battalion or battery cannot establish survey control by
the time required, hasty methods may be used. The effects
of using hasty methods and the guarantee of accurate fire
support are shown in Table 1-2. Hasty survey techniques
are completely explained in FM 6-50.
Table 1-2. Hasty survey effect on fire support
MEANS OF DETERMINING
TYPE OF
SURVEY
ORIENTATION
LOCATION
EFFECTS
Graphic resection.
Map spot.
1. No common grid.
2. No passage of target records or
registration data.
3. No guarantee on unobserved or
nonadjusted fire.
A scheme in which orientation is
initiated by theodolite to an
accuracy of 0.3 mil and more
than one fire unit is put on
common orientation. (Can be
passed by simultaneous
observation.)
Survey process that puts
more than one unit on
common grid but not
necessarily closely related to
the map. Scheme not
originated from a known
survey control point.
1. Units located in the scheme that includes
both orientation and location may pass target
records end registration data to each other.
2. No guarantee on nonadjusted or
unobserved fire unless the acquisition source
is also included in the scheme. Fire can be
messed by all units in the scheme after
adjustment with one gun.
Divisional
hasty
A scheme in which more than
one battalion is put on common
orientation.
Same as for battalion.
Same as for battalion.
Fifth-order
or higher
survey
Gyroscopic, astronomic, or
equivalent process.
Survey process that
originates at known survey
control.
1. No restriction on the passage of target
records or registration data.
2. Unobserved fire is reliable as long as the
acquisition source is in the scheme.
3. Minimizes adjustment.
Battery
hasty
Aiming circle:
Battalion
hasty
1-4
• Simulteneous observation.
• Polaris 2 reticle
observation.
• Polaris-Kochab
observation.
Ž Directional traverse.
FM 6-2
1-5. RESPONSIBILITIES OF THE
ENGINEER TOPOGRAPHIC
BATTALION
a. The engineer topo battalion is the primary source of topo
support throughout the echelons above corps (EAC). The
topo battalion responsibilities to artillery survey are as
follows:
• Extend horizontal and vertical control into corps and
division areas.
• Provide an SPCE in support of EAC.
Ž Provide mapping survey control where required.
• Advise on topo matters.
• Assist in lower-level survey to augment FA survey
when directed.
b. Topo surveyors establish and recover existing ground
control and extend it by third-order or higher conventional
survey or satellite methods. Exact positioning of this
high-order survey control is coordinated by the corps survey
officer. Topo survey support must be provided to multiple
launch rocket system (MLRS) units, corps general support
(GS) artillery units, and other nondivisional assets in the
corps area. The number of SCPs that topo survey must
provide for the EAC and corps area depends on the dispersion,
amount of movement, and commander’s priorities. For
example, on the basis of five to seven moves per day, 10
to 20 SCPs will be required every 24 hours to support EAC
and corps FA systems that div arty cannot support.
c. Topo surveyors extend survey control into the division
area of operations. Initial SCPs must be within 5 kilometers
(km) of div arty HQ. Div arty and TAB surveyors will
further extend control to the vicinity of weapon systems
and target-locating systems. Exact positioning of subsequent
SCPs depends on dispersion movement, and priorities. For
example, on the basis of five to seven moves per day, 15
to 30 points must be established or data provided from
trigonometric (trig) lists every 24 hours. At a minimum,
topo support must provide a grid network of high-order SCPs
every 30 km throughout the division or corps area. These
SCPs must also allow adjacent divisions or corps to be
connected by a common grid.
1-6. FA SURVEY ORGANIZATIONS
In the transition from personnel-intensive to equipmentintensive technology, survey organizations were tailored in
terms of mission, reliability, equipment, and personnel
requirements. The FA survey structure is the key to the
transition to new fire support systems, future survey systems,
and different unit configurations such as the light infantry
division (LID) and composite battalions. See Chapter 14
for more specific guidance on equipment and personnel
authorizations.
a. Survey Planning and Coordination Element. At the
higher echelons, there is a survey command and control cell
called the SPCE. The SPCE is authorized at each corps
artillery, div arty, FA brigade, and MLRS battalion. The
personnel that man the SPCE are shown in Table 1-3. The
SPCE plans and coordinates all of the surveys within its
area of responsibility. Survey data collection, evaluation,
and dissemination are additional functions of the SPCE.
b. Survey Platoon Headquarters. The survey platoon HQ
of FA battalions executes survey planning and coordination.
These responsibilities are carried out by an RSO (1LT), and
a chief surveyor (SFC). An FA surveyor (SPC) performs
survey functions when required and is the radiotelephone
operator (RATELO).
Table 1-3. Survey planning and coordination element
HEADQUARTERS
DUTY POSITION
RANK
Corps artillery
MAJ
SFC
SGT
SGT
SGT
Survey planning and coordination officer
Chief surveyor
Survey computer
Survey computer
Survey computer
Division artillery
(armored or mechanized)
CPT
SFC
SGT
SPC
SPC
Survey officer
Chief surveyor
Survey computer
FA surveyor
FA surveyor
Division artillery
(light or air assault airborne)
SFC
SGT
SPC
Chief surveyor
Survey computer
FA surveyor
1-5
FM 6-2
Table 1-3. Survey planning and coordination element (continued)
HEADQUARTERS
DUTY POSITION
RANK
Field artillery brigade
SFC
SGT
SPC
SPC
Chief surveyor
Survey computer
FA surveyor
FA surveyor
MLRS battalion
1 LT
SFC
SPC
Reconnaissance and survey officer
Chief surveyor
FA surveyor
Patriot battalion
SFC
SPC
Chief surveyor
FA surveyor
Note. The standards of grade authorizations, duty positions, duty titles, and tasks in AR 611-201 will change upon approval by Department
of the Army.
LEGEND:
CPT = captain
SGT = sergeant
1 LT = first lieutenant
MAJ = major
SPC = specialist
c. Survey Section. The survey section for a heavy div arty
and a 3 x 8 FA battalion consists of a section chief, one
survey team, and two PADS teams. (The duty positions
and organization for the survey sections of the different units
are shown in Figure l-l.)
(1) Section chief. The section chief (SSG) is responsible
for the total survey effort of his section. He must prioritize
his personal involvement between the survey team and the
PADS team as needed to execute the survey plan.
(2) Survey team. The survey team consists of two FA
surveyors led by the section chief. The survey team performs
conventional and modified survey methods to—
• Enhance the overall survey effort.
• speed up PADS operations.
Ž Provide flexibility and agility to the survey operation.
(3) PADS team. The PADS team, also led by the section
chief, consists of a PADS team chief and an FA surveyor.
The PADS team provides survey control as directed by the
section chief.
(4) Survey parties. Conventional survey parties (when
authorized) are configured as shown in Table 1-4.
d. Equipment Constraints. Until all PADS are fielded,
configure a survey section by using the options below.
(1) No PADS. Use a standard survey platoon HQ and
three conventional six-man parties at the div arty or five-man
survey parties at the battalion.
1-6
Table 1-4, Conventional survey parties
RANK
DUTY
POSITION
FIVE-MAN
PARTY
SIX-MAN
PARTY
SSG
Section chief
1
1
SGT
Survey
computer
1
1
SPC
FA surveyor
2
2
PFC
FA surveyor
1
2
LEGEND.
PFC = private first class
SSG = staff sergeant
(2) One PADS. Use a standard platoon HQ, a PADS
team, and two conventional six- or five-man parties.
(3) Two PADS but no SEDME-MR. Use a standard
platoon HQ, two PADS teams, and one conventional fiveor six-man party. Then, when the survey equipment,
distance-measuring, electronic (medium-range) (SEDMEMR) is issued, drop three men from the div arty or two
men from the battalion conventional party, thus forming the
standard survey section–survey section chief, one two-man
survey team, and two PADS teams.
FM 6-2
Figure 1-1. Survey sections
1-7
FM 6-2
1-7. SURVEY EQUIPMENT
The restructure of the conventional party causes a number
of changes in the tables of organization and equipment (TOE).
Table 1-5 summarizes the equipment authorized for the five
basic elements.
Table 1-5. Equipment for survey elements
1-8
FM 6-2
Table 1-5. Equipment for survey elements (continued)
1-8. DUTIES OF SURVEY PERSONNEL
Individual duties of the various survey personnel by military
occupational specialty (MOS) code or area of concentration
(AOC) are shown in Table 1-6.
1-9
FM 6-2
Table 1-6. Duties of survey personnel
SURVEY OFFICER, AOC 13D—
• Coordinates and supervises—
– Training of survey personnel.
– Field operations.
– The preventive maintenance
program on survey equipment
end vehicles.
– The SPCE, if authorized at his
echelon.
• Formulates a survey plan after
receiving orders from the S3 or
commander and before conducting
reconnaissance.
SECTION CHIEF OR CHIEF OF
PARTY, MOS 82C30— (CONTINUED)
• Supervises preventive maintenance
checks and services (PMCS) of
section equipment, to include
vehicles, communications equipment,
and weapns.
• Performs other duties as directed.
SURVEY COMPUTER, MOS 82C20—
FA SURVEYOR, MOS 82C10—
• Instrument Operator—
– Performs operator PMCS on
survey instruments.
– Operates the instruments during
field operations.
– Verifies the verticality of the range
pole before measuring angles
during field operations.
Ž Maintains the required Department of
the Army (DA) forms for computation
of surveys.
– Reads the measured values to
the recorder end checks the
recorder by use of a read-back
technique.
• Issues survey orders and briefs his
chief surveyor and team chiefs.
• Conducts reconnaissance.
• Performs Independent computations
during field operations by using the
BUCS.
– Familiarizes himself with the
fieldwork requirements for all
survey methods.
Ž Maintains the BUCS.
Ž Coordinates survey operations with
higher, lower, and adjacent HQ.
Ž Assists in the collection, evaluation,
and dissemination of survey data.
– Helps the tape team maintain
alignment during taping
operations.
CHIEF SURVEYOR, MOS 82C40—
• Performs other duties as directed.
– Performs other duties as directed.
• Computer-Recorder—
• Assists the survey officer and, when
directed, performs my or all of the
duties of the survey officer.
PADS TEAM CHIEF, MOS 82C20—
• Performs initialization, operation, and
PMCS on the PADS.
– Maintains an approved notebook
of all surveys performed by the
survey team or party.
Ž Trains his survey section in the
performance of reconnaissance,
communications, and survey
activities. Ensures that
section personnel are cross-trained.
• Sets up and operates the theodolite
when used to mark and update.
– Neatly and legibly records survey
starting data and all measured
data during field operations.
Ž Directs the assistant PADS operator
for autoreflection or plumb bob
emplacement over the SCP or other
points to be established.
– Sketches in the field notebook
concise, complete diagrams and
descriptions of the principal
stations.
Ž Performs other duties as directed.
SECTION CHIEF OR CHIEF OF
PARTY, MOS 82C30—
Ž Trains his survey party or section.
Ž Executes his party or section portion
of the survey plan.
• Supervises and coordinates field
operations of his party or section end
PADS team.
Ž Maintains liaison with the survey
officer or chief surveyor during field
operations.
1-10
Ž Records PADS data and maintains
the field notebook, ensuring all
entries conform with prescribed
format.
• Briefs assistant PADS operator and
aircraft crew on the survey mission
and zero-velocity correction
requirements.
• Performs or assists in the transfer
and strapping down of the PADS for
air assault operations.
• Performs other duties as directed.
– Checks and means angular data
measured by the instrument
operator.
– Checks taped distances by
pacing (for fifth-order surveys
only).
– Provides required field data to the
survey computers independently.
– Performs other duties as directed.
• Rodman-Tapeman—
– Maintains the FA survey set.
– Assisted by another member of
the party and using proper taping
techniques, tapes horizontal
distances during field operations.
FM 6-2
Table 1-6. Duties of survey personnel (continued)
FA SURVEYOR, MOS 82C10—
(CONTINUED)
– Computes an accuracy ratio for
double-taped distances as
required,
– Reports measured distances to
the recorder.
– Assists In setting up and marking
survey stations.
– Erects the survey equipment
distance-measuring electronic
reflector.
– Assists the instrument operator in
the care of the instruments.
– Operates and maintains
communications equipment.
– Performs other duties as directed.
• Assistant PADS Operator—
– Operates and performs
maintenance on the PADS vehicle
as specified in technical manuals.
– Operates and maintains
communications equipment.
Maneuvers vehicle for
autoreflection or plumb bob
emplacement over the SCP or
points to be established under the
direction of the PADS operator.
Sets up range poles and
establishes survey stations as
directed by the PADS operator.
Helps the PADS operator in the
transfer and strap down of the
PADS for air assault operations.
Assists the PADS operator in all
his duties.
Performs other duties as directed.
1-11
FM 6-2
CHAPTER 2
DISTANCE DETERMINATION
In conventional survey operations, a primary requirement of the survey party
is to determine distance between two points. The surveyor has many devices
available with which to determine distance. These range from the 30-meter
steel tape to electronic instruments. Using the solution of geometric figures
by methods such as trig traverse is discussed in Chapter 5. Distance
measurement is a basic operation that every FA surveyor must be able to
perform with the tools available.
Section I
HORIZONTAL TAPING
Horizontal taping is used in conventional FA surveys. In this method, all measurements are made
with the tape held horizontally. Measure the horizontal distance between the rear station and the
forward station. Usually the distance between stations is more than a full tape length. The taping
team determines the distance by measuring successive full tape lengths. When the distance remaining
is less than a full tape length, the team measures the partial tape length. The total distance between
the stations is determined by multiplying the number of full tape lengths by the length of the tape
and adding the partial tape length.
2-1. TAPING TEAM
A taping team consists of two men—a front tapeman and
a rear tapeman. The rear tapeman commands the taping
team and records all distances in his taping notebook. He
is responsible for determining and reporting the measured
distance to the recorder. The front tapeman independently
computes the distance measured. Then he compares his
findings with those of the rear tapeman and records the
distance in his notebook. At night, taping requires additional
personnel to assist the front and rear tapemen (paragraph
2-18).
2-2. TAPES AND ACCESSORIES
a. Survey taping teams are equipped with 30-meter steel
tapes for measuring linear distances. Tapes are graduated
on one side in meters, decimeters (0.1 meter), and centimeters
(0.01 meter). The first decimeter is graduated in millimeter
(0.001 meter). At each end of the tape is a blank space.
Each tape is assigned a number that is used for all records
about that specific tape (for example, repairs [paragraph
2-20b]).
b. In addition to a tape, each team is equipped with the
following (Figure 2-l):
Ž One set of taping pins.
• One tension handle.
• One clamping handle.
Ž Two plumb bobs.
Ž Two pin and plumb bob holders.
• One hand level.
• Two leather thongs.
• Two notebooks.
• Two pencils.
2-1
FM 6-2
Figure 2-1. Taping equipment
(1) Taping pins. A taping pin is a steel pinpointed on
one end with a ring at the other. Use taping pins for marking
measured tape lengths on the ground. This will help
determine the number of tape lengths measured since the
last station. The ring and the upper part of the pin are
painted red. The rest of the pin is white. Taping pins are
issued in sets of 11 pins each. Properly used, taping pins
will prevent a “missed” or “dropped” tape length, a common
mistake in distance taping.
(2) Tension handle. The tension handle is used to train
taping personnel to recognize when 25 pounds of tension
is exerted on a tape. Do not use it in normal everyday
surveys. The tension handle has a linear scale graduated
in pounds from 0 to 30. Clip it to the tape loop at the end
of the tape. Apply tension until the specified reading (25
pounds for artillery survey) appears on the scale.
(3) Clamping handle. This is a mechanical device that
grips the flat steel tape without causing a kink in it. When
measuring less than a full tape length, the clamping handle
permits holding the tape while applying tension.
(4) Plumb bobs. Plumb bobs are used to transfer tape
readings to a ground position. This will allow the tape to
be read directly above a marked position on the ground.
(5) Pin and plumb bob holders. Each tapeman uses a
pin and plumb bob holder to carry taping pins during taping
operations. Store the plumb bob in the holder when taping
operations are not performed.
(6) Hand level. Use the hand level when taping distances
over steep slopes to help keep the tape on a horizontal plane.
Use it in normal taping operations to train new tapemen to
recognize the required horizontal plane.
(7) Leather thongs. Attach a leather thong to each end
of the tape. The leather thongs allow the tapemen to apply
tension to the tape.
(8) Notebooks and pencils. Each tapeman keeps a
notebook to record distances between stations. These
notebooks are in addition to the recorder’s notebook.
(9) Other equipment. Often, taping will require the use
of other equipment. To get a straight-line clearance between
taping points, tapemen may have to clear away vegetation.
Useful cutting tools, such as axes, hatchets, or machetes,
may be issued to the taping team. Use range poles for
aligning the tape from station to station. When measuring
distances at night, use flashlights to help align the tape.
2-2
FM 6-2
(1) Sight through the level at the upslope tapeman.
2-3. TAPE ALIGNMENT
a. The tapemen must carefully align the tape. The maximum
allowable error in both horizontal and vertical alignment is
0.5 meter from one station to the next. The rear tapeman
usually makes final alignment by sighting along the tape
toward the forward station. The rear tapeman will direct
the front tapeman left or right. (See Figure 2-2.) However,
if the rear tapeman cannot see the forward station, the front
tapeman will make the final alignment. This is done by
sighting back on the rear station. The rear tapeman, using
preselected reference points aligned with the forward station,
can also make the final alignment. The instrument operator,
if available, may help in the alignment.
(2) Raise or lower the objective end of the hand level
until the image of the level bubble is centered on the horizontal
crossline.
b. The tapemen then level the tape horizontally by holding
it parallel to an estimated horizontal plane. If they have
trouble keeping the tape level in rough terrain, the tapemen
should use the hand level. To use the hand level to set a
horizontal plane, the downslope tapeman takes the steps below.
c. The tapemen should check the accuracy of the bubble of
the hand level when it is first used each day. The upslope
tapeman uses the hand level to sight on the downslope tapeman
to establish the horizontal plane. The procedure is then
reversed to verify the established horizontal plane.
(3) Determine the point on the upslope tapeman that is
level with the eye. This establishes the horizontal plane.
(4) Tell the upslope tapeman how to hold his end of
the tape so that the tape will be parallel to the established
horizontal plane. The downslope tapeman must hold the
tape no higher than his armpits. Otherwise, the team must
use the breaking tape procedure.
Figure 2-2. Tape alignment
2-3
FM 6-2
2-4. APPLYING TENSION TO TAPE
a. The tapeman must apply 25 pounds of tension (pull) to
each full or partial tape length. He should apply tension
to the tape by using his leg muscles and the large muscles
of his back. To do this, the tapeman faces across the tape
with his shoulders parallel to the length of the tape. He
then passes the hand of the arm that is away from the other
tapeman through a loop in the thong. Then he places the
elbow of that arm tight against some part of his body. (See
Figure 2-3.) When the tapeman is standing, he applies tension
by bending the knee that is away from the other tapeman.
This causes the weight of his body to push against the arm
holding the tape. When the tapeman is kneeling, he applies
tension by pushing the knee that is away from the other
tapeman against the arm holding the tape.
b. The clamping handle is used to hold the tape at arty
point other than a tape end. To avoid causing a kink in
the tape, the tapeman should hold the clamping handle with
the index and middle fingers. Normally, the handle will
clamp as he applies tension to the tape. To apply more
pressure, the tapeman applies pressure to the outside of the
finger grip by using the thumb and ring finger.
c. The front tapeman should use the tension handle until
both tapemen become accustomed to the application of 25
pounds of tension.
Figure 2-3. Applying tension and use of plumb bobs
2-4
FM 6-2
2-5. USE OF PLUMB BOBS
a. The tapemen use plumb bobs to project points on the
tape to the ground. Each tapeman holds the plumb bob
cord on the proper tape graduation using the thumb of one
hand on the cord and the forefinger of that hand beneath
the tape. (See Figure 2-3.) The front tapeman has the 0-meter
graduation and the rear tapeman has the 30-meter graduation.
After aligning the tape and applying tension, each tapeman
lowers the plumb bob by letting the cord slip across the
tape. The tip of the plumb bob should be about 0.25 inch
above the desired point. Swinging of the plumb bob is
stopped by gently lowering the tape until the plumb bob
tip touches the ground and then slowly raising the tape.
b. The rear tapeman uses his plumb bob to position his end
of the tape directly over the point from which each tape
length is measured.
c. The front tapeman establishes the point on the ground
to which each tape length is measured by dropping his plumb
bob. If necessary, the front tapeman should clear high grass
or other debris in the immediate ground area near the point
to be established. This will ensure a true plumb over the
point and help the rear tapeman in moving forward. After
establishing the point with the plumb bob, the tapeman marks
the point with a taping pin.
2-6. USE OF TAPING PINS
The front tapeman must use the taping pins to mark points
on the ground for each full or partial tape length. The front
tapeman marks the point struck by the tip of the plumb bob
by sticking a pin into the ground at exactly that point. The
shaft of the pin is placed at an angle of about 45° to the
ground and perpendicular to the length of the tape. When
moving forward, the tapeman should not pull the tape through
the loop of the taping pin. In taping over a hard surface,
it may be necessary to mark the point struck by the plumb
bob in an identifiable fashion (point of taping pin). The
point of the pin is laid at the point struck by the plumb
bob, perpendicular to the line of direction of the tape.
2-7. MEASURING THE FIRST FULL TAPE
LENGTH
Measure the first full tape length as discussed below.
a. The front tapeman gives 1 taping pin to the rear tapeman
and keeps 10 pins. The pin given to the rear tapeman represents
the first full tape length. The front tapeman moves toward
the forward station with the zero end of the tape.
b. As the end of the tape reaches the rear station, the front
tapeman stops, either on his count of paces or on the command
TAPE given by the rear tapeman. The rear tapeman aligns
the front tapeman by sighting first toward the forward station
and then in an estimated horizontal plane. Align the tape
within 0.5 meter of the line of sight from one station to the
next and within 0.5 meter of the horizontal plane.
c. Each tapeman places a leather thong on his wrist and
the plumb bob cord on the proper graduation on the end of
the tape. The rear tapeman aligns his plumb bob roughly
over the rear station and commands PULL. The tapemen
exert a pull of 25 pounds on the tape.
d. After the tapemen have properly aligned and applied tension
to the tape, the rear tapeman plumbs his end of the tape
exactly over the rear station and commands STICK. At
this command, the front tapeman drops his plumb bob and
then marks the point of impact by inserting a taping pin
into the ground. Insert the pin perpendicular to the line of
measurement at an angle of about 45° to the ground. This
allows accurate plumbing for the next measurement. After
the pin is firmly placed, the front tapeman announces STUCK.
This is the command for the rear tapeman to move forward
to the pin position. The front tapeman advances 30 paces
to measure the next tape length.
2-8. MOVING FORWARD
a. The front tapeman should select a landmark (rock, bush,
or such) in line with the forward station. Use this technique
as a guide in moving forward. The front tapeman should
keep his eyes on the forward station. He should determine
his pace count for one tape length. He can stop without
signal from the rear tapeman when he has moved forward
a tape length.
b. By moving forward to a point 2 or 3 meters forward of
the rear end of the tape, the rear tapeman usually can locate
the taping pin before the front tapeman has stopped. If the
taping pin is not readily visible, the front tapeman may have
to wait until the rear tapeman arrives at his position. Then
he moves forward to make the next measurement.
c. When using an instrument at either the forward or the
rear station, the tapeman must remain as clear of the line
of sight as possible.
2-9. MEASURING SUCCEEDING FULL
TAPE LENGTHS
Succeeding full tape lengths are measured as described in
paragraph 2-7 except as discussed below.
a. The front tapeman should get his approximate horizontal
alignment by sighting back along the tape toward the last
pin position and the rear station. This will allow him to
move right or left until the tape is about on line.
2-5
FM 6-2
b. The rear tapeman plumbs the end of the tape exactly
over the point at which the taping pin enters the ground.
c. After the front tapeman commands STUCK, the rear
tapeman pulls the taping pin from the ground and then moves
forward to the next pin position. If a taping pin is lost
during the measurement of the distance, the tapemen must
tape the entire distance again rather than complete the taping
from a recovered pinhole.
2-10. BREAKING TAPE
When the tape alignment is unobtainable within 0.5 meter
of a horizontal plane because of the slope of the ground,
the tapemen use a special procedure known as breaking tape.
(See Figure 2-4.) The procedure for breaking tape is discussed
below.
a. The front tapeman pulls the tape forward a full length.
He then drops it about on line and then walks back along
the tape until he reaches a point at which a partial tape
length can be measured. When the tape is held level, it
should be no higher than the armpits of the downslope tapeman.
At that point, the front tapeman selects any convenient full
meter graduation. The tapemen then measure the partial
tape length, aligning the tape and applying the full 25-pound
tension. Clamping handles are used at any holding point
between ends of the tape.
b. After he has placed the taping pin into the ground, the
front tapeman announces STUCK. He then waits until
the rear tapeman comes forward. The front tapeman tells
the rear tapeman which full meter graduation was used; for
example, HOLDING 25. The rear tapeman repeats
HOLDING 25. The front tapeman receives a pin from the
rear tapeman and moves forward. Tapemen repeat this
procedure until they reach the zero mark on the tape.
c. When holding a point on the tape other than the zero
graduation, the front tapeman must receive a pin from the
rear tapeman before moving forward.
2-11. MEASURING DISTANCES MORE
THAN 10 TAPE LENGTHS
To measure a distance longer than 10 full tape lengths, the
tapemen use the procedures described in paragraphs 2-3
through 2-9 except as discussed below.
a. When the front tapeman has set his last pin in the ground,
he has established a point that is 10 full tape lengths from
the rear station. The front tapeman waits at the last pin
position until the rear tapeman comes forward.
b. Both tapemen count the pins to be sure that none are
lost. (One pin in the ground will not be counted. The rear
tapeman should have 10 pins.)
Figure 2-4. Breaking tape
2-6
FM 6-2
c. The rear tapeman gives the front tapeman the 10 pins.
d. Both tapemen record 10 tape lengths (300 meters) and
then continue taping.
2-12. MEASURING PARTIAL TAPE
LENGTHS
To measure the partial tape length between the forward station
and the taping pin representing the last full tape length, the
tapemen use the procedure discussed below.
a. The front tapeman moves to the forward station and places
the plumb bob cord on the zero graduation of the tape. The
rear tapeman moves forward along the tape to the taping
pin.
b. To gain slack, the front tapeman commands SLACK.
The rear tapeman allows the tape to move forward. When
the front tapeman is ready, he commands PULL. The rear
tapeman exerts a pull of 25 pounds on the tape, using a
clamping handle to hold the tape. Then the rear tapeman
slides his plumb bob cord along the tape until the plumb
bob is exactly over the pin.
c. When the zero graduation is exactly over the forward
station, the front tapeman commands READ. The rear
tapeman reads the graduation marked by his plumb bob cord
and announces the measurement of the partial tape length
to the nearest 0.01 meter.
d. The front tapeman repeats the reading aloud, and both
tapemen record the measurement.
e. If the survey party has a nonstandard tape that is graduated
in millimeters (mm) from the zero end to the 1-meter mark
and in decimeters from the l-meter mark to the 30-meter
mark, or in any other combination, use the procedure discussed
below.
(1) The front tapeman holds the plumb bob on zero.
(2) The rear tapeman, using a clamping handle to hold
the tape, places his plumb bob cord on the first whole meter
mark behind the last pin in the ground.
(3) The rear tapeman commands PULL, and the front
tapeman exerts a pull of 25 pounds on the tape. The rear
tapeman should give slack until his plumb bob is exactly
over the last pin. The front tapeman slides his plumb bob
cord along the tape until the plumb bob is over the forward
station.
(4) When the rear tapeman’s plumb bob (which he holds
on a whole meter mark) is exactly over the pin, the rear
tapeman commands READ. The front tapeman reads the
graduation marked by his plumb bob cord and announces
his partial meter reading. The rear tapeman announces the
whole meter mark that he was holding.
2-7
FM 6-2
(5) Computing independently, both tapemen subtract the
front tapeman's partial meter reading from the rear tapeman’s
whole meter reading. After verifying the amputations by
comparison, both tapemen record the distance.
f. When a taping team is making a measurement at a station
occupied by an instrument, the tapeman can make the
measurement at the plumb bob cord of the instrument. The
tapeman must use extreme care not to disturb the instrument.
2-13. DETERMINING TAPED DISTANCE
The tapemen determine and check the distance measurement
(Figure 2-5) as discussed below.
a. Each tapeman counts the number of pins he has. (The
pin in the ground at the last full tape length is not counted.)
b. The rear tapeman determines the distance measurement.
He does this by multiplying the length of the tape (30 meters)
by the number of pins in his possession and adding the
partial length read from the tape.
c. The front tapeman independently checks the distance
measurement. He does this by first subtracting the number
of pins in his possession from 10, then multiplying by 30,
and adding the partial tape distance.
Figure 2-5. Determining taped distance
2-8
FM 6-2
2-14. USE OF TWO TAPING TEAMS
2-16. TAPING ACCURACIES
When two taping teams measure the distance between two
stations, one taping team uses a pin to establish a starting
station one-half tape length (15 meters) from the rear station.
In this case, the front tapeman does not give a pin to the
rear tapeman. The taping pin marking the half tape length
represents one full tape length plus 15 meters. After
establishing the starting station a half tape length from the
rear station, the taping procedures are the same as those
described earlier except that each tapeman adds 15 meters
to the distance measurement. This procedure prevents both
teams from placing their taping pins in the same hole.
To achieve the various degrees of accuracy in survey, distances
must be determined accurately to certain specifications,
depending on the method of survey used. Prescribed accuracies
for the different methods of survey are listed in Appendix
B.
2-15. COMPARATIVE ACCURACY FOR
DOUBLE-TAPED DISTANCES
a. When the distance between two stations has been
determined by double-taping, the two measurements are
compared and the comparative accuracy of the two
measurements is determined. The comparative accuracy is
expressed as a ratio between the difference in the measurements
and the mean of the measurements. The ratio is expressed
with a numerator of 1; for example, 1/1000 or 1:1,000. The
denominator is determined by dividing the mean of the
measurements by the difference in the measurements. After
the comparative accuracy is computed, the denominator of
the fraction is reduced to the next lower hundred.
b. When the double-taped distance does not meet the required
comparative accuracy, the distance must be taped a third
time. Then the third measurement is compared with each
of the first two measurements to determine if a satisfactory
comparative accuracy can be achieved, with one or the other,
The unsatisfactory distance is discarded.
2-17. ERRORS
Horizontal taping errors fall into three groups-systematic
errors, accidental errors, and errors caused by blunders.
a. Systematic Errors. Systematic errors are errors that
accumulate in the same direction. They can be measured
and normally are constant in each tape length.
(1) The systematic errors in horizontal taping cause
distance to be measured longer or shorter than the true length.
The main causes of systematic errors are as follows:
Ž Failure to align the tape properly.
Ž Failure to apply enough tension to the tape.
• Kinks in the tape.
• Tape of incorrect length (a little short or a little
long).
(2) Eliminate systematic errors by strict adherence to
proper procedures and techniques. Tapemen should be
especially careful to keep the tape horizontal when taping
on a slope and should break tape when necessary. They
should avoid the tendency to hold the tape parallel to the
slope. When taping in strong winds, tapemen must be
especially careful to apply the proper tension to the tape.
Tapes should be checked often for kinks. One of the chief
causes of kinked tapes is improper use of the clamping handle.
(3) Systematic errors can be due to improper tape repair
(repaired too long or too short). This causes taped distances
to be longer or shorter than the true distances.
b. Accidental Errors. Accidental errors involve probability
and may accumulate in either direction. Usually, these errors
are minor and tend to offset each other. Small errors in
plumbing cause the principal accidental error. Tapemen should
be careful in plumbing over points. When taping in strong
winds, they must be especially careful to reduce swinging
of the plumb bob. The tapeman does this by keeping the
plumb bob close to the ground and shielding the plumb bob
as much as possible with his leg.
c. Errors Caused by Blunders. Blunders are major errors
made by poorly trained or careless soldiers. A blunder may
be an error in any direction. Correct this by remeasuring
the distance.
2-9
FM 6-2
(1) The main blunders made by tapemen are as follows:
• Incorrect exchange of taping pins.
• Errors in reading the tape.
• Omission of the half tape length when two teams
are double-taping.
• Loss of a taping pin.
Ž Failure of front and rear tapemen to compare
distance measured.
(2) Blunders are detected and eliminated by strict
adherence to correct taping procedures.
2-18. TAPING AT NIGHT
During night operations, three additional men are added to
each taping team. One man goes with each tapeman as a
light holder. The third man places the taping pin in the
ground. When the rear tapeman comes forward to the taping
pin, the third man walks the length of the tape and frees
the tape from any obstacles. This procedure is repeated for
each full or partial tape length. A piece of white cloth may
be tied to each end of the tape to help the tapemen follow
and locate the tape. Light holders must observe light discipline
when using their lights.
2-19. MAINTENANCE OF STEEL TAPES
a. Steel tapes are accurate surveying instruments, and you
must handle them with care. Although steel tapes are of
durable construction, they can be easily damaged through
improper care and use. Never let a vehicle run over a tape.
b. When a steel tape is used, it should be completely removed
from its reel and kept straight to prevent kinking or breaking.
The tape should never be pulled around an object that will
cause a sharp turn in the tape. Care should be taken to avoid
jerking or stepping on the tape. Applying tension with a
loop in the tape may cause the tape to kink or break. Before
applying tension, the tapemen must be sure there are no
loops in the tape.
c. The tape should be wiped clean and dry and oiled lightly
after each use. The tape is oiled by running it through an
oily rag while rewinding the tape on its reel. The tape
should be loosely wound on its reel when not in use. When
rewinding the tape, the tapeman should insert the end of
the tape with the 30-meter graduation into the reel and wind
the tape so the numbers are facing the axle of the reel.
2-10
FM 6-2
2-20. REPAIR OF BROKEN TAPE
a. You can protect tapes and maintain them. However, at
one time or another, you may have to repair one in the field
to avoid delay in the work. For this reason, every survey
party should have a tape repair kit. This kit contains a pair
of small snips, tape sections of proper size and graduations,
and a hand punch or bench punch with block. Also included
are an assortment of small rivets, a small container of sheet
metal sleeves, a pair of tweezers, and a small hammer. (See
Figure 2-6.) When repairing a broken tape, first square the
broken ends. Next, align the broken tape ends over the
spare tape section so the graduations are the correct distance
apart. Select a spare tape section long enough to span the
distance between the squared ends and to overlap each end
not less than 3 centimeters. When using rivets, rivet each
overlap so the edges of all parts of the points are snug. To
do this, place the rivets near (about 3 mm from) the squared
ends. A broken tape can also be repaired by fitting a sheet
metal sleeve over the broken ends of the tape. The sleeve
is coated on the inside with solder and flux. When the sleeve
is hammered down tightly and heat is applied, the solder
securely binds the broken ends of the tape within the sleeve.
You can use an ordinary match to heat the solder. Repair
of tapes with rivets is considered a permanent repair. A
repair with metal sleeves is considered a temporary repair.
b. Compare the repaired tape with another tape to ensure
proper joining of the tape ends and that the tape gives a
true measurement. Any discrepancy between the two tapes
is recorded in the taping notebook and is referenced to the
tape number mentioned earlier.
Figure 2-6. 30-meter steel tape repair kit
2-11
FM 6-2
Section ll
SURVEY EQUIPMENT, DISTANCE-MEASURING,
ELECTRONIC (MEDIUM-RANGE)
Survey sections equipped with the SEDME-MR can measure distances in minimum time. The
SEDME-MR is a compact, lightweight, economical, and simple-to-operate instrument that is
especially suitable for short- and medium-range survey operations. Measuring distances from 30
to 7,000 meters takes about 18 seconds measuring time under average conditions.
2-21. DESCRIPTION OF COMPONENTS
The SEDME-MR consists of the distance meter and the
retroreflector prisms. These units mount on any universal
tripod. The distance meter and the retroreflectors are
packaged and transported in separate carrying cases—the
distance meter case and the restoreflector cases.
a. Distance Meter Case. The distance meter case (Figure
2-7) contains the items of equipment discussed below.
(1) Distance meter. The distance meter is the electronic
package of the system. This instrument generates and sends
a modulated signal and receives the reflected signal from
Figure 2-7. Distance meter case contents
2-12
FM 6-2
the prism. The calculated slope distance is in meters and
appears on the numerical display.
(2) Batteries. Issued with each system are two
nickel-cadmium (NICAD) batteries. You can make about
750 continuous measurements with each battery before
recharging is necessary.
(3) Battery charger. A battery charger comes with the
system and is used to recharge fully discharged batteries.
(4) Connector cable. The connector cable allows
simultaneous charging of both batteries.
(5) External power cable. The external power cable
permits the distance meter to connect to and get power from
an external 12-volt battery.
(6) Tribrach. The tribrach adapts the distance meter and
retroreflectors to the tripod.
Note. Carrying case design reduces the chance of
damage to the instrument and the accessories in
transport. Pack all equipment properly in the carrying
case before transporting.
b. Retroreflector Case. Two sets of retroreflectors come
with each SEDME-MR. A set of retroreflextors consists
of a three-prism cluster (triprism) and a seven-prism cluster
(heptaprism). (See Figure 2-8.) The triprism is used for
distances up to 3,000 meters. The heptaprism normally is
enough for a maximum distance of 7,000 meters under average
conditions. Average atmospheric conditions are considered
to be light haze with visibility of about 15 km or moderate
sunlight with light heat waves.
Figure 2-8. Retroreflector case contents
2-13
FM 6-2
2-22. SETTING UP THE SEDME-MR
The setup procedure for the SEDME-MR uses issued tribrachs
and/or the theodolite tribrach for the distance meter and prism.
After measuring the station angle, follow the steps below.
Refer to Figure 2-9 for the location of controls and indicators
of the distance meter.
a. Remove the theodolite from the tribrach by using the
tribrach clamp. Replace and secure the theodolite in its
case.
current (v DC) power source, and connect the black clip
lead to the negative terminal of the DC power source.
f. Set the parts per million (PPM) switches to 00 (atmospheric
correction not used in artillery survey).
g. Set the OFFSET switch to the instrument offset
correction. (An instrument offset correction is stamped onto
the instrument offset plaque located at the bottom left corner
of the instrument.)
b. Mount the distance meter on the tribrach and lock it in
place by using the tribrach clamp. Check the tribrach leveling
bubble, and relevel if necessary.
h. Accurately set the retroreflector up over the point to which
you are making the distance measurement. Align the
retroreflector on the line of sight to the instrument. (See
Figure 2-10.)
c. Adjust the vertical lock and horizontal lock firmly enough
to allow holding action.
2-23. OPERATING PROCEDURES
d. When using the NICAD battery, place the battery pack
onto the instrument power connector.
e. When using the auxiliary cable, connect the power cable
to the power connector. Connect the red clip lead of the
power cable to the positive terminal of the 12-volt direct
a. Test. An automatic test function is built into the instrument.
The test provides a quick check of the internal microcomputer
and display circuits. To test, press the PWR switch to turn
on the instrument. The instrument enters the test mode
automatically. The numerical display should sequence from
all 0s to all 9s and then display 0000.
Figure 2-9. SEDME-MR controls and indicators
2-14
FM 6-2
Figure 2-10. Prism alignment
(4) Repeat steps (2) and (3) above until the SIG meter
indicates no further increase.
Note. To achieve maximum range accuracy, correctly
sight the Instrument on the retroreflector.
(5) As the last step in the acquisition procedure, press
the CAL-START switch and wait for the READY light to
come on. When the READY light comes on, the
SEDME-MR is ready for distance measurement.
c. Ranging. After sighting the instrument on the retroreflector and maximizing the return signal, the operator
performs the steps below.
b. Retroreflector Acquisition. After completion of the test
function, the SEDME-MR is ready for alignment on the
retroreflector.
CAUTION
Do not aim the SEDME-MR directly at the sun.
The optical system of the SEDME-MR is designed
for infinity focus. You may damage the sensitive
detector located at the focal point of the receiver
optics.
(1) Using the vertical and horizontal tangent screws,
position the sighting scope reticle on the prism. For shorter
distances, the sighting point should be 4.5 inches above the
retroreflector. When the retroreflector is first acquired and
a return signal is received, an audio tone will sound for
about 2 seconds and then go off. The audio tone will sound
again each time the return signal falls below a predetermined
level after initial acquisition.
(2) While squiring the retroreflector, note the indication
on the signal (SIG) meter. Carefully adjust the vertical and
horizontal tangent screws to maximize the SIG meter
indication.
(3) If the pointer of the SIG meter runs up against the
upper stop because the signal level is too great, press the
CAL-START switch. The READY lamp should light, and
the meter pointer should automatically move to about
midscale before the vertical and horizontal tangent screws
are adjusted further. Near the maximum range of the
instrument, the meter pointer may indicate below center;
however, if the READY lamp is on, measurements can be
made.
(1) Press the AIM-RANGE switch. Be very careful not
to move the instrument. The AIM light should go out. The
SEDME-MR will begin to cycle automatically. A slight
clicking sound will indicate that the measurement is
occurring. In about 6 seconds, the measured distance will
appear on the numerical display.
(2) Read aloud the displayed distance to the recorder.
Ensure the recorder reads back the distance correctly. If
the recorder repeats the distance incorrectly, immediately
announce CORRECTION and repeat the correct distance
measurement.
(3) The instrument will continue to make distance
measurements automatically and will update the range
indication on the numerical display every 6 seconds as long
as the instrument remains in the range mode. Read and record
two more distance measurements.
(4) Check the recorded distances to be sure that there
is no variation among the three readings of more than 0.010
meter from the mean. If any of the readings is outside this
limit, take another reading to replace it.
(5) TO stop the range sequence, press the AIM-RANGE
switch to select the aim mode or press the PWR switch to
turn off the instrument.
Note. The audio tone will not function in the range
mode of operation.
d. Slope Distance Conversion. The mean of the three
distances is a slope distance and must be converted to a
horizontal distance. There are two different means of converting
the slope distance to a horizontal distance.
(1) TO compute the required distance, use the formula
D = cos V x S. In this formula, D is horizontal distance,
V is the vertical angle between the distance meter and the
2-15
FM 6-2
reflector, and S is slope distance. These computations may
be made with logarithms or with the BUCS. The horizontal
distance determined from this computation meets the
accuracy requirements for field artillery.
(2) The horizontal distance can also be determined by
using Program 2 (Traverse) of the BUCS survey module
and DA Form 5591-R (Computation of Coordinates and
Heights From Azimuth, Distance, and Vertical Angle
(BUCS)). (A reproducible copy of this form is at the back
of this book.) When using the BUCS to convert the distance,
perform the following steps:
Step 1. Call Program 2.
Step 2. Press the END LINE key at the TRAVERSE
prompt.
under such conditions. This allows a gradual temperature
change.
c. Lens Care. Use care in cleaning dust or moisture from
lenses. Do not touch lenses with fingers. Do not use coarse
cloth, paper, or other material that might scratch the lenses.
Use antistatic optical cleaning cloth, lens tissue, and a
camel‘s-hair brush. Use a mild soap and water solution to
remove smudge marks, when needed. To further protect
lens, keep lens cover on when not in use.
d. Nickel-Cadmium Battery. A NICAD battery was
selected for use in the power unit. A NICAD battery, with
proper care, performs good over an extended lifetime. To
charge the battery, follow the instructions in (1) through (5)
below.
Step 3. Bypass the E OCC STA: 0.00 prompt by pressing
the END LINE key.
Step 4. Bypass the N OCC STA: 0.00 prompt by pressing
the END LINE key.
Step 5. Bypass the HT OCC STA. 0.0 prompt by
pressing the END LINE key.
Step 6. Bypass the AZ TO REAR: 0.000 prompt by
pressing the END LINE key.
CAUTION
Do not try to charge a battery that is not fully
discharged. Ensure each battery is fully discharged
by using it until a distance can no longer be
measured due to the lack of power. Trying to charge
a partially charged NICAD battery will shorten the
life of the battery.
Step 7. Respond to the prompt MN SCH LEG (Y/N) by
entering Y or N.
Step 8. Bypass the prompt HZ FWD: 0.000 by pressing
the END LINE key.
Step 9. At the prompt VA (+/-): 0.000, enter the vertical
angle.
Step 10. Respond to the prompt RECIP VA (Y/N) by
entering Y or N.
Step 11. At the prompt ˆDIST FWD (-:SL/+:HZ), press
the END LINE key. When the screen becomes blank, enter
the slope distance. Remember to enter the distance as a
negative number.
Step 12. At the next step, BUCS will display the
horizontal distance.
2-24. CARE AND MAINTENANCE
a. Packing and Transporting. Pack the SEDME-MR in
the molded carrying case with the foam inserts provided.
The SEDM-MR should be packed for transport or when it
is not in use.
b. Condensation. Taking an instrument from a cold to a
warm environment can cause condensation on the instrument.
Leave the instrument in its carrying case for several hours
2-16
(1) Plug the battery charger into an alternating current
(AC) power outlet that is continuously supplied with power.
The battery charger is designed to operate from a nominal
110-volt, 50/60-hertz (Hz) power supply. When only a
220-volt, 50/60-Hz source is available, use the 220/110-volt
adapter supplied with the unit.
CAUTION
Before plugging the battery charger into an AC
power outlet, make certain that the rating of the
battery charger matches the rating of the available
AC power source.
(2) Plug the connector end of the battery charger cable
into the power connector unit. On a battery charger that
has a red charge light, the light should come on. This indicates
that the unit is taking a charge.
(3) Allow about 16 hours to completely recharge a fully
discharged battery with the supplied battery charger.
FM 6-2
(4) Leaving the battery unit plugged into the battery
charger will not cause overcharging. However, during
prolonged periods of inactivity, disconnect the charged
battery from the power unit and store it.
(3) Turn the instrument power on, and select the aim
mode. If there is no signal indication, search the area near
the prism until the signal is squired. Use the tangent screws
to maximize the signal.
(5) To prevent possible damage to the NICAD battery,
never charge it in an area where the temperature falls below
5 degrees Celsius (C) (40 degrees Fahrenheit [F]) or exceeds
27°C (90°F).
(4) Remove the covers from the vertical and horizontal
cross hair adjustment screws.
Note. While the battery unit is charging, the battery
charger may become warm to the touch and may
emit a buzzing sound. This is normal. It is not an
indication of a malfunction In the battery charger.
(6) Using the vertical adjustment screw, move the
horizontal cross hair to a point 4.5 inches above the center
of the prism. (See Figure 2-11.)
e. Sighting Telescope Alignment. Adjust the alignment
of the sighting telescope as discussed below.
(7) After adjustments, use the tangent screws to obtain
maximum strength and ensure proper alignment. Replace
covers on the adjustment screws.
(1) Place a single-prism or triple-prism cluster with only
the center prism uncovered at a distance of 30 to 50 meters
from the SEDME-MR.
(2) Using the vertical and horizontal tangent screws,
position the telescope cross hairs on the center of the
uncovered prism.
(5) Using the horizontal adjustment screw, position the
vertical cross hair to the center of the prism.
f. Power Fuse. The power fuse protects the power circuits
of the SEDME-MR against overload. If the power fuse
fails, power is no longer applied to the internal circuits. If
you see no response when operating the PWR switch, check
or replace the fuse. If repeated fuse failures occur, turn the
SEDME-MR in for repair.
Figure 2-11. Telescope alignment
2-17
FM 6-2
g. BATT Light. Flashing of the BATT light indicates a
low battery. The instrument operator can still make reliable
range measurements with the light flashing. However, the
instrument will go into an automatic power-off mode when
battery voltage falls below a preset limit. At that point, the
BATT light will glow brightly and steadily. Connection of
a recharged battery unit or an auxiliary source to the
instrument will permit resumption of normal operation.
Note. In low ambient light conditions, a faint glow
may be observed. This is normal end does not indicate
low battery voltage.
2-18
FM 6-2
CHAPTER 3
ANGLE DETERMINATION
An FA survey operation consists of many tasks. One task is the
measurement of horizontal and vertical angles. Field artillery surveyors
use two angle-measuring instruments—the T16 and the T2 theodolites.
Section I
T16 THEODOLITE
The T16 and T16-84 theodolites (Figure 3-1) are compact, lightweight dustproof, optical-reading,
directional-type instruments equipped with a fixed reticle (Figure 3-2) in the telescope and a horizontal
circle (repeater) clamp. Surveyors use these theodolites to measure horizontal and vertical angles
for artillery fifth-order survey. The horizontal and vertical scales of the theodolite are enclosed
and are read through a built-in optical system. The scales, graduated in mils, are read directly to
0.2 mil (m) and by estimation to the nearest 0.1 mil. Illumination of the scales is provided by
either sunlight or artifical light.
3-1. ACCESSORIES
Accessories issued with the T16 include the following:
Ž Canvas accessory kit, which contains the following:
Note. For detailed information on the T16 theodolite,
see TM 5-6675-200-14 or TM 5-6675-270-15.
Eyepiece prisms.
3-2. PREPARING THE T16 THEODOLITE
FOR USE
Sun filters.
a. Set up the tripod as discussed below.
Two jeweler’s screwdrivers.
Two adjusting pins.
(1) Upend the tripod, place the tripod head on the toe
of your boot, and unbuckle the restraining strap.
Camel’s-hair brush.
Lubricant.
(2) Loosen the leg clamp thumbscrews, and extend the
tripod legs to the desired length. Tighten the leg clamp
thumbscrews. Do not force the thumbscrews.
Plastic instrument head cover.
Circular compass.
Two operation and service manuaIs.
Ž Battery case with lighting devices and three spare
bulbs.
• Universal tripod with plumb bob, plug-in sleeve,
and tripod key in a leather pouch attached to the
tripod.
In addition to the accessories issued with the older model
T16, the T16-84 accessories include a GST20 tripod and
an eye prism. The fixing screws on all Wild tripods have
the same threads. This allows both theodolites to mount on
any Wild tripod.
(3) Spread the legs, and place the tripod over the occupied
station with one leg bisecting the angle(s) to be measured.
Set up the tripod head so that the telescope will be at a
convenient height for the operator.
(4) Insert the plug-in sleeve of the plumb bob into the
instrument fixing screw. The plumb bob should hang about
1 inch above the station. Center the tripod approximately
over the station.
(5) Firmly embed the tripod legs in the ground. Be sure
the plumb bob is within 0.5 inch (laterally) of center of the
station. The tripod head should be approximately level when
the legs are embedded.
(6) Remove the tripod head cover.
3-1
FM 6-2
Figure 3-1. T16 and T16-84 theodolites
3-2
FM 6-2
b. Remove the theodolite from its case as discussed below.
(1) Grasp the carrying strap with both hands just above
the two clamping levers. Pull outward to release the clamping
levers from the base assembly.
(2) Lift the dome-shaped cover directly off the
instrument, and lay it to one side.
(6) Return the instrument to the second position (Figure
3-4), and again center the bubble.
(7) Repeat (5) and (6) above until the bubble remains
centered in both positions.
Figure 3-2. Telescope reticle
(3) Pull upward on the two base clamping levers that
secure the theodolite to the base assembly. Grasp the
theodolite by the standard on which the trademark is
inscribed, and lift the theodolite off the base assembly.
Handle the theodolite by this standard only.
Note. The carrying handle is used to lift the T16-84
theodolite off the base assembly.
(4) Attach the instrument to the tripod head by screwing
the fixing screw snugly into the base of the tribrach.
(5) Replace the cover on the carrying case to keep dust
and moisture from entering the case. Move the case away
from the tripod to provide a working area for the instrument
operator.
c. Plumb and level the T16 theodolite as discussed below.
(1) Loosen the fixing screw slightly, and carefully move
the instrument around on the tripod head to center the point
of the plumb bob exactly over the station.
(2) Tighten the fixing screw. Be sure the point of the
plumb bob remains centered over the station. Remove the
plumb bob, and return it to its case.
Figure 3-3. Leveling the theodolite-first and third
positions
CAUTION
Excessive tightening of the fixing screw will bend the
slotted arm and damage the tripod head.
(3) Loosen the horizontal clamping screw, and rotate the
instrument until the axis of the plate level is parallel to any
two of the three leveling screw knobs. This is the first
position. Center the bubble by using these two leveling screw
knobs. Grasp the leveling screw knobs between the thumb
and forefinger of each hand. Turn the knobs simultaneously
so the thumbs of both hands move either toward each other or
away from each other. (See Figure 3-3.) This movement
tightens one screw as it loosens the other. The bubble always
moves in the same direction as the left thumb.
(4) Rotate the instrument 1,600 mils. This second
position places the axis of the tubular level at a right angle to
the first position. Using the third leveling screw knob only,
center the bubble. (See Figure 3-4.)
Figure 3-4. Leveling the theodolite-second and
fourth positions
(5) Return the instrument to the first position (Figure
3-3), and again center the bubble.
3-3
FM 6-2
(8) Rotate the instrument 3,200 mils from the first
position (Figure 3-3) so the axis of the tubular level vial is on
a line parallel with the first position. If the bubble remains
centered in this position, rotate the instrument 3,200 mils from
the second position. (See Figure 3-4.) If the bubble remains
centered in this position, rotate the instrument throughout
6,400 mils. The bubble should remain centered. If the
instrument remains centered, it is level.
(9) Rotate the instrument 3,200 mils from the first
position ((8) above). The level vial is out of adjustment if it
does not remain centered. If time permits, perform a plate
level adjustment. If the situation does not allow time for a
plate level adustment, perform the following. To
compensate, with the instrument in this position (Figure 3-3),
move the bubble halfway back to the center of the level vial
by using the same two leveling screw knobs used for the first
position. Rotate the instrument 3,200 mils from the second
position, and move the bubble halfway back to the center of
the level vial by using the one remaining leveling screw knob.
Rotate the instrument through 6,400 mils. If the bubble does
not move more than one graduation, the instrument is
considered level. If the bubble moves more than one
graduation, repeat the leveling procedure. If the bubble
continues to move more than one graduation, turn the
theodolite in to the supporting maintenance unit for repair.
(10) After the instrument is level, cheek the optical plumb
to ensure that the instrument is centered exactly over the
station. If it is not, center the instrument over the station by
loosening and shifting it on the tripod head. Check the level
of the instrument. If necessary, repeat the leveling process,
and again check the optical plumb. Repeat this process until
the instrument is level and centered over the station.
Note. A valid check with the optical plumb can be
made only if the optical plumb is in proper adjustment.
3-3. TAKING DOWN THE T16
THEODOLITE
After completing observations at a station, march-order the
theodolite and tripod as discussed below.
a. Remove the dome cover from the carrying case.
b. Place the telescope in a vertical position with the objective
lens down, and lightly clamp the vertical clamping screw.
c. Turn the leveling screws halfway down and to the same
height.
d. Position the horizontal clamping screw directly over one
of the leveling screws, and lightly clamp it.
Note. On the T16-84, place the optical plumb over
any one of the leveling screws.
3-4
FM 6-2
e. Close the illumination mirror, and turn the hinge to the
top.
f. Hold the instrument by its right standard, and unscrew
the instrument-fixing screw. Lift the theodolite from the
tripod, and secure it in the carrying case. Replace the
dome-shaped cover.
g. Replace the tripod head cover, collapse the tripod, and
strap the tripod legs together.
Figure 3-5. T16 theodolite scales viewed through the
circle-reading microscope
3-4. READING AND SETTING
HORIZONTAL AND VERTICAL
CIRCLES WITH THE T16
a. With the T16 theodolite prepared for observing as
described in paragraph 3-2, open the illumination mirror.
Adjust the light so both the horizontal and vertical circles
are uniformly illuminated when viewed through the
circle-reading microscope. When operating at night with
unfavorable lighting, attach lighting devices and connect them
to the battery pack. Adjust the focus of the circle-reading
microscope until the numbers on the horizontal and vertical
scales are sharp and clear.
b. When viewed through the circle-reading microscope
(Figure 3-5), the vertical circle (marked “V”) appears above
the horizontal circle (marked “AZ”). Both circles are
graduated from 0 to 6,400 mils with a major graduation
each 10 mils. Unit mils and tenths are viewed on an auxiliary
scale graduated in 0.2-mil increments from 0 to 10 mils.
Circle readings are estimated to the nearest 0.1 mil. The
scale reading is taken at the point where the major (10-mil)
graduation (gauge line) is superimposed on the auxiliary
scale. When the telescope is not in a horizontal position,
the scales will appear tilted. The amount of tilt depends
on the inclination of the telescope.
Figure 3-6. T16-84 scales viewed through the circlereading microscope
Note. The horizontal circle of the T16-84 theodolite
(Figure 3-6) is yellow and marked “HZ.”
c. All horizontal angle measurements with the T16 theodolite
begin with an initial circle setting of 0001.0 mil on the
horizontal circle. This practice prevents working with a
negative mean of direct (D) and reverse (R) readings on the
rear station. To set this value on the horizontal circle, release
the horizontal clamping screw and rotate the instrument until
the major graduation 0 appears on the horizontal circle.
Tighten the horizontal clamping screw, and use the horizontal
tangent screw to set the 0 gauge line directly over the 1.0-mil
graduation on the auxiliary scale. Engage the horizontal
circle clamp by setting it to the locked position (down).
The horizontal circle is now attached to the alidade of the
instrument. The reading of 0001.0 mil will remain on the
horizontal circle as long as the horizontal circle clamp is
engaged.
3-5
FM 6-2
3-5. FOCUSING THE TELESCOPE TO
ELIMINATE PARALLAX
3-6. MEASURING HORIZONTAL ANGLES
WITH THE T16
Before using the theodolite to measure angles, focus the
telescope to eliminate parallax. Parallax is eliminated by
bringing the focus of the eyepiece and the focus of the
objective lens to the plane of the reticle (crosslines). To do
this, first point the telescope toward the sky or a neutral
background. Rotate the knurled ring on the telescope
eyepiece until the reticle cross lines are distinct lines. When
doing this, be very careful to focus your eyes on the crosslines,
not on the sky. Next point the telescope toward a
well-defined distant point. While focusing on the crosslines,
bring the distant point into a clear, sharp image by rotating the
knurled focusing ring on the telescope. Use the horizontal
tangent screw to center the vertical crossline on the point. To
check for parallax, move your eye horizontally back and forth
across the eyepiece. If parallax is eliminated, the crossline
will remain fixed on the object as you move your eye. If all
parallax is not eliminated, the crossline will appear to move
back and forth across the object. To eliminate any remaining
parallax, change the focus of the eyepiece slightly to bring the
crosslines into sharper focus and refocus the telescope
accordingly until there is no apparent motion. Each time an
angle is measured, the telescope should be focused to
eliminate parallax. Accurate pointings with the instrument
are not possible if parallax exists.
a. In artillery survey, the T16 theodolite is used as a
directional-type instrument. The horizontal circle clamp is
used only to set the initial circle setting (0001.0 roil) on the
horizontal circle before making a pointing on the initial
station. Measuring horizontal angles consists of determining,
at the occupied station, the horizontal circle readings to each
observed station, beginning with an initial (rear) station. The
angle between two observed stations is the difference between
the mean (inn) horizontal circle readings determined for each
of the observed stations. The mean horizontal circle readings
used to determine the angles are determined from two
pointings (circle readings) on each observed station. (See
Figure 3-7.)
b. The direct and reverse pointings on each station should
differ by 3,200 roils, plus or minus the amount of horizontal
spread (twice the actual error in horizontal collimation) in
the instrument. No value can be specified as the maximum
allowable spread for an instrument however, it should be
small (1.0 mil or less) for convenient in meaning of the
pointings. The amount of the spread should be constant;
otherwise, there are inconsistencies in operating the
instrument. If the mean spread of an instrument exceeds
1.0 mil, the instrument should be adjusted at the first
opportunity.
Figure 3-7. Field notebook extract and sketch of pointings in measuring horizontal angles
3-6
FM 6-2
c. With the telescope in the direct position, the initial circle
setting of 0001.0 mil on the horizontal circle, and the
horizontal circle clamp engaged (down), make a pointing
on the initial, or rear, station at the lowest visible point.
This establishes the direction of the station at 0001.0 mil
with respect to the horizontal circle. Record in the field
notes (Figure 3-7) the value of the direct reading on Station
A. Release (lift) the horizontal circle clamp. This causes
the horizontal circle to detach itself from the alidade and
remain in its fixed position. Then make a pointing on each
station around the horizon in a clockwise direction. After
making a pointing to the last station, plunge the telescope
to the reverse position (by rotating the telescope to an upside
down position). Make a pointing on each station in a
counterclockwise direction, beginning with the last station
and ending with the initial station. This sequence of
operations is defined as a one-position angle.
d. In making pointings, the horizontal and vertical clamping
screws are used to place the crossline approximately on the
object marking the station. After placing the crosslines
approximately on the target, tighten the horizontal and vertical
clamping screws. Then use the horizontal and vertical
tangent screws to plain the crosslines exactly on the lowest
visible point of the station. (See Figure 3-8.) The final
rotation of the tangent screws must be in a clockwise direction.
Note. The view through the T16-84 is the same as the
T16 except that the view is not inverted.
Figure 3-8. Crosslines on the lowest visible point
3-7
FM 6-2
c. After making the reverse pointing on the initial station
and recording the horizontal circle reading, plunge the
telescope to the direct position. Then make a direct pointing
on the initial station. Although zeroing the instrument is
not a part of the angle measurement it will save time in
setting the initial circle setting for the angle measurement
at the next station.
3-7. DETERMINING VERTICAL ANGLES
WITH THE T16
a. Normally, each time a horizontal angle is measured, a
vertical angle to the forward station is determined. If
possible, measure vertical angles to the height of the
instrument.
b. Vertical angles cannot be measured directly with the
theodolite. The vertical circles of the theodolite reflect
readings of 0 mils at the zenith (straight up), 1,600 mils
horizontal direct, 3,200 mils at the nadir (straight down),
and 4,800 mils horizontal reverse. Hence, values read from
the vertical circle are not vertical angles but are zenith
distances that are converted to vertical angles. When the
collimation level bubble is centered, vertical circle readings
are taken from what is, in effect, an upward extension of
the plumb line of the theodolite. (See Figure 3-8.) One
value of the vertical angle is computed from the vertical
circle reading made with the telescope in the direct position
arid pointed at the station. With the telescope in the direct
position, a vertical circle reading of less than 1,600 mils
indicates that the station observed is above the horizontal
plane of the theodolite and the vertical angle is positive. A
vertical circle reading greater than 1,600 mils indicates that
the station observed is below the horizontal plane of the
theodolite and the vertical angle is negative. To determine
the value of a positive vertical angle, subtract the vertical
circle reading from 1,600 mils. (See Figure 3-9, (A).)
Determine the value of a negative vertical angle by subtracting
1,600 mils from the vertical circle reading. (See Figure 3-9,
(B).) A second value of the vertical angle is computed
from the vertical circle reading made with the telescope in
the reverse position and pointed at the station. With the
telescope reversed, a vertical circle reading greater than 4,800
mils indicates a positive vertical angle, and a vertical circle
reading less than 4,800 mils indicates a negative vertical
angle. Determine the value of a positive vertical angle by
subtracting 4,800 mils from the vertical circle reading, (See
Figure 3-9, (C).) Determine the value of a negative vertical
angle by subtracting the vertical circle reading from 4,800
mils. (See Figure 3-9, (D).) Mean the two values by adding
them together and dividing the result by two. The result
is the vertical angle to the observed station.
Figure 3-9. Relation of vertical circle readings and vertical angle
3-8
FM 6-2
c. After placing the crosslines on the station, elevate or
depress the telescope until the horizontal crossline is exactly
on the point to which the vertical angle is desired. After
positioning the telescope on the station, center the bubble
of the collimation level (split bubble) on its vial by rotating
the collimation level tangent screw until the images of the
ends of the bubble coincide. (See Figure 3-10.) Then read
the vertical circle reading in the circle-reading microscope.
The T16-84 has an automatic vertical index.
Note. If the T16-84 instrument is so off Ievel that the
automatic index is no longer within its working range, a
red warning screen appears on the vertical circle scale.
If a red screen appears, relevel the instrument.
Figure 3-10. View of collimation level
3-8. COMPUTING HORIZONTAL AND
VERTICAL ANGLES
After making the direct and reverse pointings and recording
the horizontal and vertical circle readings in the field notes
(Figure 3-7), determine the size of each angle.
a. To determine the horizontal angle between Stations A
and B (Figure 3-7), first determine the mean of the pointings
on each station. Do this by mentally adding 3,200 mils to,
or subtracting 3,200 mils from, the reverse reading and taking
the mean of the direct and reverse readings. Enter the results
in the field notes in the proper column. Then determine
the horizontal angle between the stations by finding the
difference in the mean circle readings. In Figure 3-7, the
mean pointing on Station A is 0001.0 mil; on Station B,
0229.4 mils. Therefore, the horizontal angle from Station
A to Station B is 0228.4 mils (0229.4-0001.0 = 0228.4).
b. In the field notes in Figure 3-7, the direct pointing on
Station B resulted in a vertical circle reading of 1,596.5
mile, or a vertical angle of +1.5 mils. With the telescope
revered, the vertical circle reading on Station B was 4,601.4
mils, or a vertical angle of +1.4 mils. The mean vertical
angle from the instrument to Station B is +1.4 mils (1.5 +
1.4 + 2 = 1.45 rounded to the nearest even 0.1 mil =1.4.
3-9
FM 6-2
3-9. CARE OF THE T16 THEODOLITE
The T16 theodolite is a delicate instrument. Take care not
to drop it or bump it against any object. If the instrument
gets wet, dry it before storing it in the carrying case. As
soon as possible, place the instrument in a dry room or tent.
Remove it from the carrying case so it can dry completely.
If left in the closed carrying case, it will absorb the humidity
in the air if there is an increase in temperature. Should the
temperature drop later, the moisture will condense on the
inside of the instrument and may render the instrument
inoperable. A man on foot may carry the instrument mounted
on the tripod from station to station. Always carry the
theodolite in an upright position. Clamp all motions with
the telescope in the vertical position. For transport over
rough terrain, the instrument should be in its carrying case.
When transported in a vehicle, the theodolite should be in
the carrying case and the case should be in the padded box,
For short distances in vehicles, the instrument operator may
hold the carrying case in an upright position on his lap.
3-10. CLEANING THE T16 THEODOLITE
Keep the theodolite clean and dry. During use, as necessary,
and after use, clean the instrument as discussed below.
a. Wipe painted surfaces with a clean cloth.
b. Clean the lenses only with a camel’s-hair brush and lens
tissue. Clean the lenses first with the brush to remove any
dust or other abrasive material and then with the lens tissue.
Remove any smudge spots remaining after using lens tissue
by slightly moistening the spot and again cleaning with lens
tissue. Be careful not to scratch the lenses or remove their
coating. The coating reduces glare for the observer.
Ž Plate level test and adjustment.
Ž Optical plumb teat and adjustment.
Ž Horizontal collimation teat and adjustment.
Ž Vertical collimation test and adjustment.
When a test indicates that an adjustment is necessary, the
operator makes the adjustment and retests the instrument
for accuracy before making the next test in sequence.
b. The four tests and adjustments of the theodolite are made
with the instrument mounted on its tripod. For these tests
and adjustments, set the instrument up in the shade on firm
ground with the head of the tripod as nearly level as possible.
Also protect the theodolite from the wind.
c. If handled properly, an instrument will remain in
adjustment indefinitely. Needless and excessive movement
of the adjusting screws will cause them to become worn
and the instrument will not hold an adjustment.
3-13. T16 PLATE LEVEL TEST AND
ADJUSTMENT
a. Purpose. The purpose of the plate level adjustment is
to make the vertical axis of the theodolite truly vertical when
the bubble of the plate level is centered in the vial. (See
Figure 3-11.)
Figure 3-11. Plate level adjustment
c. Clean all metal parts of the tripod with a cloth moistened
with an approved cleaning solvent. Then wipe them dry.
Clean the wooden parts with a soft cloth moistened with
water, and dry the parts thoroughly. Clean the leather strap
with a suitable leather cleaner.
3-11. REPAIR OF THE T16 THEODOLITE
Theodolites in need of major adjustment or repair should
be turned in to the engineer unit responsible for providing
maintenance service.
3-12. TESTS AND ADJUSTMENTS OF
THE T16 THEODOLITE
a. Keep the T16 theodolite in correct adjustment to obtain
accurate results. There are four tests and adjustments of
the T16 theodolite that the instrument operator must make.
He makes these tests and adjustments in the following
sequence:
3-10
b. Test.
Step 1. Test the adjustment of the plate level by placing
the axis of the plate level bubble parallel to any two
of the three leveling screws. (See Figure 3-12.)
FM 6-2
Figure 3-12. Plate level adjustment, step 1
Step 2. With these two leveling screws, center the
bubble in its vial. Rotate the instrument 1,600 mils,
and align the plate level with the third leveling screw.
(See Figure 3-13.)
Figure 3-13. Plate level adjustment, step 2
Figure 3-14. Plate level adjustment, apparent error
c. Adjustment. To adjust the plate level, use the adjusting
pin from the accessory case. With the instrument 3,200
mils from the first position insert the adjusting pin into the
hole of the capstan screw and remove one-half of the apparent
error (actual error) by turning the capstan adjusting screw.
On the T16 theodolite, the plate level adjusting screw is
about 1.5 inches above the horizontal clamping screw on
the right standard. (See Figure 3-15.) After adjusting, repeat
the plate level test and adjust as necessary to correct any
error remaining in the plate level bubble. The plate level
is in proper adjustment when the bubble remains centered
throughout 6,400 mils rotation.
Figure 3-15. Plate level adjusting screw
and adjusting pin
Step 3. Center the bubble in this position by using
the third leveling screw. Rotate the instrument back
to the first position, and see if the bubble remains
centered. Repeat leveling in these two positions until
the bubble remains centered in both positions.
Step 4. Carefully rotate the instrument 3,200 mils from
the first position. If the bubble does not remain
centered within one graduation, an adjustment is
required. The discrepancy noted between the position
of the bubble and the center position is the apparent
error, or twice the actual error of the plate level. The
level vial has graduated lines used to determine the
apparent error. (See Figure 3-14.)
3-11
FM 6-2
Note. On the T16-64, the plate level adjustment screw
is on the top right of the plate level vial. (See Figure
3-16.)
Figure 3-16. Plate level adjusting screw (T16-84)
b. Test.
Step 1. To test the optical plumb, set up the theomdolite
over a station that is clearly marked by a cross or
other well-defined point. Accurately plumb and level
the instrument. The image of the point should be
centered exactly in the center of the optical plumb.
This is accomplished by recentering and releveling as
necessary.
Step 2. When the instrument is leveled and the image
of the point is centered, rotate the alidade 6,400 mils
about its vertical axis. If the image of the point does
not remain centered in the reticle, an adjustment is
required. The amount of displacement is the apparent
error, or twice the actual error, of the optical plumb.
Position the instrument at the point where the
displacement is farthest from the point.
c. Adjustment.
Step 1. To adjust the optical plumb, correct one half
of the displacement (actual error) by turning the two
optical plumb adjusting screws. The adjusting screws
are 1.25 inches to the right and left of the optical
plumb eyepiece. To gain access to the adjusting
screws, remove the cover screws. (See Figure 3-18.)
3-14. T16 OPTICAL PLUMB TEST AND
ADJUSTMENT
a. Purpose. The purpose of the optical plumb adjustment
is to make the vertical axis of the theodolite pass through
the station mark when the theodolite is properly leveled and
the station mark is centered in the reticle of the optical plumb.
(See Figure 3-17.)
Figure 3-17. Optical plumb adjustment
3-12
Figure 3-18. Optical plumb eyepiece
and cover screws
FM 6-2
Step 2. Use the screwdriver from the accessory case to
turn the adjusting screws. Loosen the adjusting screw
on the side opposite the side to which the reticle must
be moved. Tighten the other screw, and the reticle moves
as the screw is tightened. Move the reticle image one-half
the distance to the station mark by moving first one screw
and then the other in small increments. The last
movement of both adjusting screws must be clockwise.
This compresses a counterspying positioned under each
screw and holds the optical system stationary.
Step 3. Check the adjustment again by centering the
instrument over the station mark and leveling it. Rotate
the instrument through 6,400 mils. If the image of the
reticle remains centered on the station mark throughout
the full circle, the optical plumb is in adjustment. If the
image of the reticle does not remain centered on the
station mark throughout the full circle, repeat the
adjustment until the image of the reticle remains centered.
After the adjustment is complete, replace the cover screws.
Figure 3-20. Horizontal collimation
adjustment, step 1
3-15. T16 HORIZONTAL COLLIMATION
TEST AND ADJUSTMENT
Step 2. With the telescope in the direct position, center
the vertical crossline on the selected point. Read the
horizontal circle reading to the recorder.
For
illustration purposes, assume your direct reading is
0001.0 mil.
a. Purpose. The purpose of the horizontal collimation
adjustment is to make the line of sight perpendicular to the
horizontal axis of the telescope. (See Figure 3-19.)
Step 3. Plunge the telescope to the reverse position,
and give the recorder a second reading to the same
point. Assume the reverse reading is 3,202.6 mils.
Figure 3-19. Horizontal collimation adjustment
Note. Only one sat of direct and reverse readings is
required.
Be very careful, therefore, to prevent
pointing or reading errors.
Step 4. The difference between the direct and reverse
readings should be exactly 3,200 mils. Assuming you
did not make any error in the pointings or readings,
the discrepancy between the actual difference in the
two readings and 3,200 mils is the apparent horizontal
collimation error, or twice the actual horizontal
collimation error.
If the apparent horizontal
collimation error exceeds the initial circle setting
(0001.0 mil for the T16), you should perform the
horizontal collimation adjustment.
EXAMPLE
b. Test.
Step 1. To test the horizontal collimation, select a
well-defined point at least 100 meters (m) from the
instrument and at about the same height as the instrument.
(see Figure 3-20.)
Direct reading to
selected point
Reverse reading to the
same point
Spread (0002.6 -0001 .0)
Apparent horizontal
collimation error
Actual error (apparent error
divided by 2) (1.6 + 2)
0001.0
3202.6-3200 = 0002.6
1.6
1.6 mils
0.8 mil
3-13
FM 6-2
c. Adjustment.
Step 1. With the telescope sighted on the point in the
reverse position and using the horizontal tangent screw,
set the circle to the mean value of the direct and reverse
pointings. (Mean reverse reading: 3202.6- 0.8= 3201.8)
This will move the vertical crossline of the telescope
reticle off the point.
Step 2. Move the vertical crossline back to the point by
turning the two pull-action capstan adjusting screws that
are arranged horizontally and on opposite sides of the
telescope near the eyepiece. To move the crosslines to
the left, loosen the right screw first and tighten the left
screw. If the adjusting screw is tightened too much, it
will cause the reticle to get out of adjustment later. Do
not try to make the entire adjustment in one step. Loosen
and tighten the opposite screws in small amounts. Do
this until the crossline is centered exactly on the sighted
point.
Figure 3-21. Vertical collimation adjustment
Figure 3-22. Vertical collimation adjustment, step 1
Note. On the T16-84, the cover on the telescope
eyepiece must be removed to expose the capstan
adjusting screws.
Step 3. Perform the test again, and make additional
adjustments until the difference is less than 0.2 mil.
Note. It is preferred that the adjustment be made with
the theodolite in the reverse position. This adjustment
also can be made with the telescope in the direct
position and by using the mean value for the direct
pointing (0001.0+0.8 = 0001.8).
3-16. T16 VERTICAL COLLIMATION
TEST AND ADJUSTMENT
a. Purpose. The purpose of the vertical collimation
adjustment is to make the line of sight horizontal when the
vertical circle reading is 1,600 mils with the telescope in
the direct position (4,800 mils with the telescope in the reverse
position) and the ends of the collimation level bubble in
alignment. (See Figure 3-21.)
b. Test.
Step 1. To test the vertical collimation, select a
well-defined point at least 100 meters from the instrument
and about on a horizontal plane with the theodolite. (See
Figure 3-22.)
Step 2. With the telescope in the direct position, give
the recorder a direct vertical circle reading to the point.
Be sure to precisely align the collimation level bubble.
Step 3. Plunge the telescope to the reverse position. Give
the recorder a reverse circle reading to the same point.
Be sure the collimation level bubble is precisely aligned
before you read the vertical circle. Check the alignment
after you take your reading.
3-14
Note. Only one set of direct and reverse readings is
required.
Be very careful, therefore, to prevent
pointing or reading errors.
c. Adjustment. The sum of the direct and reverse readings
should be 6,400 mils. Any difference between the sum of
the two readings and 6,400 mils is the apparent vertical
collimation error, or twice the actual error. If the difference
exceeds 0001.0 mil for the T16 theodolite, the vertical
collimation level should be adjusted. To compensate for
the error, you must compute the correct vertical pointing
by using the two vertical readings. If the sum of the two
readings is greater than 6,400 mils, determine the difference
between the sum and 6,400 mils. Then subtract one-half
the difference from your reverse reading to obtain a corrected
reading. If the sum of the two readings is less than 6,400
mils, find the difference between the sum and 6,400 mils.
Add one-half of the difference to the reverse vertical reading.
FM 6-2
EXAMPLE
1603.4
Direct reading
+4797.8
Reverse reading
6401.2
Sum
-6400.0
Apparent error
1.2 mils
0.6 mil
Actual error (1.2 + 2)
Corrected reverse vertical 4,797.2 mils
reading (4797.8 - 0.6)
EXAMPLE
Direct reading
1594.6
+4804.2
Reverse reading
Sum
6398.8
1.2 mils
Apparent error (6400 - 6398.8)
0.6 mils
Actual error (1.2 + 2)
Corrected reverse vertical
4,804.8 mils
reading (4804.2 + 0.6)
Step 1. With the instrument in the reverse position
and the telescope sighted on the selected point, use
the collimation level tangent screw to place the
corrected vertical reading on the vertical circle scale.
The collimation level bubble will not be centered.
Step 2. Remove the cover from the collimation level
bubble, and use the capstan adjusting screw to center
the collimation bubble. Rotate the single adjusting
screw to align the images of the collimation bubble.
On the T16-84, slacken the screw located 1/2 inch
above the illumination mirror and open the cover. The
adjustment screw for the vertical index is now seen.
Turn the adjustment screw carefully until the correct
vertical reading is set, then close the cover.
Step 3. Continue the test and adjustments until the
difference between the direct and reverse readings is
less than 0.2 mil.
Note. It is preferred that the adjustment be made with
the theodolite in the reverse position. This adjustment
also can be made with the telescope in the direct
position b using the corrected direct vertical reading
to adjust the instrument.
3-17. TESTS AND ADJUSTMENTS OF
THE T16-64 THEODOLITE
a. There are five tests and adjustments on the T16-84
theodolite that are made by artillery survey personnel. The
tests and adjustments are performed in the following order:
3-15
FM 6-2
Ž Plate level adjustment.
Ž Circular bubble test and adjustment.
Ž Optical plumb test and adjustment.
Ž Horizontal collimation test and adjustment.
Ž Vertical collimation test and adjustment.
The procedure for tests and adjustments on the T16-84 are
very similar to those of the T16. Perform the plate level,
horizontal collimation, and vertical collimation tests and
adjustments by following the procedures outlined for the
T16 theodolite in paragraphs 3-13, 3-15, and 3-16
respectively.
b. Always perform the tests and adjustments in the sequence
in which they are listed. After you make an adjustment,
perform the test again to check for accuracy before you go
to the next teat and adjustment. When making adjustments,
do not force the movement of the adjusting screws or exert
too much pressure. The screws could be damaged and render
your instrument unserviceable.
A correctly adjusted
theodolite is essential in obtaining accurate survey results.
3-18. T16-84 CIRCULAR BUBBLE TEST
AND ADJUSTMENT
a. Purpose. The purpose of the circular bubble adjustment
is to make the circular bubble center of its setting circle
when the plate level is in adjustment.
b. Test. Level the instrument by using the plate level. The
circular level should be center of its setting circle. If not,
it must be adjusted.
c. Adjustment. To adjust the circular bubble, tighten and/or
loosen the two small adjustment screws in the side of the
level holder (Figure 3-23) until the level is centered in its
setting circle.
Figure 3-23. Circular level adjusting screws
3-19. T16-84 OPTICAL PLUMB TEST
AND ADJUSTMENT
a. Purpose. The purpose of the optical plumb adjustment
is to make the vertical axis of the theodolite pass through
the station mark when the theodolite is properly leveled and
the station mark is centered in the reticle of the optical plumb.
b. Test.
Step 1. Place a piece of paper on the ground under
the instrument. Accuratel y plumb the instrument by
using the plumb bob, and mark the point on the paper.
Label the mark “Point l.”
Step 2. Remove the plumb bob, and bring the point
into focus. Turn the leveling screws to set the cross
hairs of the optical plumb exactly on Point 1. Move
the eye slightly to ensure there is no parallax between
the cross hairs and Point 1. If there is parallax, adjust
the focus.
Step 3. Rotate the alidade 3,200 mils, and carefully
mark the position of the cross hairs on the paper as
Point 2. If Points 1 and 2 coincide, the optical plumb
is in adjustment. If not, it must be adjusted.
c . Adjustment.
Step 1. Mark a point (Point 3) halfway between points
1 and 2. Using the leveling screws, set the cross hairs
of the optical plumb on Point 3.
Step 2. Loosen the four screws in the plate around
the optical plumb eyepiece until the optical plumb and
plate can just move. (See Figure 3-24.)
Figure 3-24. Optical plumb
Step 3. Move the plummet and plate carefully until
the cross hairs are exactly on Point 1. Tighten the four
screws. Repeat the test, and if necessary, repeat the
adjustment.
3-16
FM 6-2
Note. In the procedure described above, the plate
level has no influence and must be ignored.
CAUTION
It may be difficult for you to remember where the
various adjusting screws are located when you need
to make adjustments on the theodolite. You should
always refer to the technical manual published for
each type of theodolite.
3-20. CARE AND USE OF THE TRIPOD
The tripod should be used and cared for as discussed below.
a. Turn the tripod to its upright position. Test the adjustment
of the tripod legs by elevating each leg, in turn, to a horizontal
position and then releasing it. If properly adjusted, the leg
should fall to about 800 mils and stop. If it does not, adjust
the tripod leg by tightening or loosening the tripod clamping
nut. Repeat the test until it is successful.
b. Clean the wooden parts with a soft cloth moistened with
water, and dry them thoroughly. Clean the leather strap with
a suitable leather cleaner.
Section II
T2 THEODOLITE
The T2 theodolite (Figure 3-25) is the authorized angle-measuring instrument for artillery fourth-order
survey. The theodolite is a directional-type instrument and is used to measure horizontal and
vertical angles. It has interior scales, which are read by means of a built-in optical system. The
scales, graduated in mils, can be read directly to 0.002 mil and by interpolation to the nearest
0.001 mil. The scales may be illuminated by sunlight or by means of a built-in wiring system
using artificial light. All parts of the instrument that can be seriously damaged by dust or moisture
are enclosed. The T2 theodolite is issued with a canvas accessory case containing the following:
Figure 3-25. T2 theodolite
3-17
FM 6-2
Ž An instructional pamphlet.
Ž Diagonal eyepieces for the telescope and reading
microscope.
Ž A sun filter.
Ž A jeweler’s screwdriver.
Ž Two adjusting pins.
Ž A camel’s-hair brush.
Ž A plastic instrument cover.
(3) Turn the leveling screws about halfway down and
to the same height.
(4) Lightly clamp the horizontal clamping screw.
(5) Close the illumination mirrors, and turn the hinges
to the top.
(6) Hold the instrument by its right standard, and unscrew
the instrument-fixing screws. Lift the theodolite from the
tripod, and secure it in the carrying case. Replace the
dome-shaped cover.
Ž Two lamp fittings for artificial illumination.
(7) Replace the tripod head cover, collapse the tripod,
and strap the legs together.
Also issued with the T2 is a battery case containing lighting
devices and spare bulbs and a universal tripod with a plumb
bob, plug-in sleeve, and tripod key in a leather pouch attached
to the tripod. The accessories of some models of the
theodolite are stored in the base of the carrying case.
3-22. CIRCLE READINGS WITH THE T2
a. A system of lenses and prisms permits the observer to
Note. For detailed information on the T2 theodolite,
see TM 5-6675-205-20P, TM 5-6675233-20P, and TM
5-6675-296-14.
3-21. PREPARING AND TAKING DOWN
THE T2 THEODOLITE
a. Setting Up the Tripod. The tripod used with the T2
theodolite is similar to that used with the T16 theodolite.
The procedure for setting up this tripod is the same as that
for setting up the T16 theodolite tripod (paragraph 3-2).
b. Removing the Theodolite From Its Case. The T2
theodolite is removed from its case in the same manner as
the T16 theodolite (paragraph 3-2) except that the T2
theodolite is fastened to the base by three supports with
locking devices.
c. Plumbing and Leveling the Theodolite. The procedure
for plumbing and leveling the T2 theodolite is the same as
that for the T16 theodolite. (See Figures 3-3 and 3-4.)
d. Focusing the Telescope to Eliminate Parallax. The
telescope of the T2 theodolite is the same as the telescope
of the T16 theodolite. It is focused to eliminate parallax in
the same manner (paragraph 3-5).
see small sections of either the horizontal circle or the vertical
circle. The circles are viewed through the circle-reading
microscope eyepiece located alongside the telescope. The
observer selects the circle to be viewed by turning the circle
selector knob on the right standard. The field of view of
the circle-reading microscope contains two small windows.
(See Figure 3-26.) The upper window shows images of
two diametrically opposite parts of the circle (horizontal or
vertical). One image of the circle is inverted and appears
above the other image. The lower window shows an image
of a portion of the micrometer scale.
b. The micrometer coincident knob on the side of the right
standard is used in conjunction with the micrometer scale
to obtain readings for either of the circles. Optical
coincidence is obtained between diametrically opposite
graduations of the circle by turning the micrometer
coincidence knob. When this knob is turned, the images
of the opposite sides of the circle appear to move in opposite
directions across the upper window in the circle-reading
microscope. The image of the micrometer scale in the lower
window also moves. The graduations of the circle (upper
window) are brought into coincidence so they appear to
form continuous lines across the dividing line. The center
of the field of view in the upper window is marked by a
fixed vertical index line. The final coincidence adjustment
should be made between circle graduations near this index
line.
e. Taking Down the T2 Theodolite. The procedure for
taking down the T2 theodolite is discussed below.
(1) Remove the dome cover from the carrying case, and
prepare the case to receive the theodolite by opening the
locking devices.
(2) Place the telescope in a vertical position with the
objective lens down, and lightly clamp the vertical clamping
screw.
3-18
3-23. HORIZONTAL CIRCLE READINGS
WITH THE T2
A reading on the horizontal circle is determined as discussed
below.
a. Rotate the circle selector knob until the black line on
the face of the knob is horizontal.
FM 6-2
Figure 3-26. T2 theodolite scales viewed through the
circle-reading microscope
a. With the circle graduations in coincidence (Figure 3-26),
determine the first erect numbered graduation to the left of
the index line that marks the center of the upper window.
This numbered graduation indicates the value of the circle
reading in tens of mils. In Figure 3-26, this graduation is
121.
b. Locate on the inverted scale the graduation for the number
opposite 121 (the number +320). In Figure 3-26, this number
is 441 (viewed as
The inverted number normally is
to the right of the index line that marks the center of the
field of view. Both values always end in the same
number—in this case, the number 1. When the unit mil of
the circle reading is zero, coincidence is obtained when the
circle reading and its diametrically opposite number are in
coincidence with each other.
c. Count the number of spaces between graduations from
121 to the inverted 441. Each of these spaces represents 1
mil. There are five spaces, representing 5 mils.
d. Convert 121, which is tens of mils, to 1,210 mils. To
this value, add the unit mils determined in paragraph c above
(1,210 + 5 = 1,215 mils, the angular value obtained from
the main scale).
e. On the micrometer scale (lower window), the index line
that marks the center of the field of view also indicates the
value to be read from the micrometer scale. In Figure 3-26,
this value is 0.475 mil.
b. Adjust the illuminating mirror so both windows in the
circle-reading microscope are uniformly lit.
c. Focus the microscope eyepiece so the graduations of the
circle and the micrometer scale are sharply defined.
d. Observe the images in the microscope eyepiece. Bring
the circle graduations into coincidence at the center of the
upper window by turning the coincidence knob.
e. Read the horizontal circle and the micrometer scale.
3-24. STEPS IN CIRCLE READING
On the T2 theodolite, the main scale (upper window) is
graduated in 2-mil increments (Figure 3-26). Each fifth
graduation is numbered with the unit digits omitted. For
example, 10 mils appears as 1; 250 mils, as 25; and 3,510
mils, as 351. The micrometer scale (lower window) is
graduated from 0.000 mil to 1.000 mil. Each 0.002 mil is
marked with a graduation and each fifth graduation is
numbered (hundredth of a mil). The scale may be read to
0.001 by interpolation. The steps in reading the circles are
discussed below.
f. Add the values determined in paragraphs d and e above
(1215 + 0.475= 1,215.475 mils, the angular value displayed
in Figure 3-26).
3-25. VERTICAL CIRCLE READINGS
WITH THE T2 THEODOLITE
To view the vertical circle, turn the circle selector knob to
the vertical position (the black line on the face of the knob
is vertical.) Adjust the vertical circle illuminating mirror
so both windows in the circle reading microscope are
uniformly lit. The vertical circle is read in the same manner
as the horizontal circle. Before reading the vertical circle,
center the vertical collimation level (split bubble) by using
the procedures described in paragraph 3-7, and bring the
images of the vertical circle into coincidence by using the
procedures described in paragraph 3-22.
3-26. SETTING THE HORIZONTAL
CIRCLE
There are two situations in which it is necessary to set the
horizontal circle.
a. The first instance is when the initial circle setting of
(0000.150 ± 0.100 mil) is used.
3-19
FM 6-2
(1) Point the instrument at the rear station.
(2) Using the coincidence knob, place a reading of 0.150
on the micrometer scale.
(3) Using the circle-setting knob, zero the main scale as
accurately as possible, ensuring that the numbered lines,
which are 3,200 mils apart (the erect 0 graduation and the
inverted 320 graduation), are touching each other. Ensure that
the circle-setting knob cover is closed when this step is
finished.
(4) With the coincidence knob, bring the main scale
graduation into precise coincidence.
(5) Read the horizontal circle. The reading should be
0000.150 ± 0.100 mil).
b. The second instance is when it is desired to orient the
instrument on a line of known direction from a reference
direction (or to measure a predetermined angle).
(1) Sight the instrument on the station for which the
reference direction is provided, and read the circle.
(2) Add the angular difference between the reference
direction and the desired direction (or the predetermined
angle) to the circle reading. The result is the circle reading
for the instrument when it is pointed in the desired direction.
(3) Using the coincidence knob, set the micrometer scale
to read the fractional portion of the desired circle reading to
the nearest thousandth of a mil.
(4) Using the horizontal clamping screw and the
horizontal tangent screw, rotate the alidade to obtain
coincidence on the main state at the roils value corresponding
to the reading obtained in (2) above. When coincidence is
obtained, the instrument is pointing in the desired direction.
3-27. MEASURING HORIZONTAL
ANGLES WITH THE T2
a. Since the T2 theodolite is a directional-type instrument,
the values of horizontal angles are determined by differences
in circle readings. The procedures for measuring and
determining horizontal angles (Figure 3-27) are discussed
below.
(1) With the telescope in the direct position, point to
the rear station (Station A). Set and record the initial circle
setting (0000.166 mil).
(2) With the telescope in the direct position, point to
the forward station (Station B). Record the horizontal circle
reading (1,215.475 mils).
(3) Plunge the telescope to the reverse position, and point
to Station B. Record the circle reading (4,415.503 mils).
(4) With the telescope in the reverse position, point to
Station A. Record the circle reading (3,200.200 mils).
Figure 3-27. Method of recording and sketch of pointings in measuring horizontal angles, T2 theodolite
3-20
FM 6-2
(5) Subtract 3,200 mils from the reverse pointing on
Station A. Mean the remainder with the direct pointing on
Station A (0000.183 mil).
(6) Subtract 3,200 mils from the reverse pointing on
Station B. Mean the remainder with the direct pointing on
Station B (1,215.489 mils).
g. When two positions are observed, if the two observed
values for any angle differ by more than 0.050 mil, these
observed values should be rejected. If the observed values
are rejected, the angles) must be remeasured.
3-28. DETERMINING VERTICAL ANGLES
WITH THE T2
(7) Subtract the mean pointing on Station A from the
mean pointing on Station B to determine the horizontal angle
from Station A to Station B (1215.489-0000.183= 1,215.306
mils).
a. The procedure for determining vertical angles with the
T2 theodolite is the same as that for the T16 theodolite
(paragraph 3-7).
Note. Steps (1) through (7) above constitute one
direct and one reverse pointing on each station, which
is referred to as one position.
b. After sighting on the observed station and with the circle
selector knob in the vertical position, make the vertical circle
reading in the same manner as the horizontal circle reading.
b. When it is necessary to measure the angle to more than
one station, make a pointing on the initial station with the
telescope in the direct position and then on each station
around the horizon in a clockwise direction. After getting
a direct reading on the last station, reverse the telescope
and make a pointing at each station in a counterclockwise
direction, ending with the initial station. One set of direct
and reverse pointings on all of the observed stations
constitutes one position.
c. The direct and reverse pointings on each station should
differ by 3,200 mils, plus or minus the amount of horizontal
spread (twice the actual error in horizontal collimation) in
the instrument. No value can be specified as the maximum
allowable spread for an instrument however, it should be
small (0.150 mil or less) for convenience in meaning the
pointings. The amount of the spread should be constant;
otherwise, there are inconsistencies in operating the
instrument. If the mean spread of an instrument exceeds
0.150 mil, the instrument should be adjusted at the first
opportunity.
d. In FA survey, one position is normall y observed for
traverse.
e. It may be necessary, as in fourth-order triangulation, to
measure two positions. The second position is measured
in the same manner as the first position, except that the
second position is measured with the telescope in the reverse
position for the initial pointing on each station. The initial
circle settings should be as follows: first position, 0000.150
(+ 0.100) mil; second position (reverse), 4,800.150 mils
(+ 0.100) mil.
f. Determine the angle between two observed stations by
measuring and meaning the horizontal circle reading to each
station and computing the difference between the mean circle
readings. When two positions are taken, determine the value
of the angle by taking the mean of the values of the angle
as determined from each of the two positions.
3-29. TESTS AND ADJUSTMENTS OF
THE T2 THEODOLITE
a. The T2 theodolite must be kept in correct adjustment
if accurate results are to be obtained. There are five tests
and adjustments of the T2 theodolite that the instrument
operator must make in the following sequence:
Ž Plate level test and adjustment.
Ž Optical plumb test and adjustment.
Ž Verticality test and adjustment.
Ž Horizontal collimation teat and adjustment.
Ž Vertical collimation teat and adjustment.
When a test indicates that an adjustment is necessary, the
operator makes the adjustment and retests the instrument
for accuracy before making the next test in sequence.
b. The Eve tests and adjustments of the theodolite are made
with the instrument mounted on its tripod and accurately
leveled. For these tests and adjustments, the instrument is
set up in the shade on firm ground with the head of the
tripod as nearly level as possible. The theodolite should
also be protected from the wind.
c. If handled properly, an instrument will remain in
adjustment indefinitely. Needless and excessive movement
of the adjusting screws should be avoided, as it will cause
the screws to time worn, and the instrument will not
hold an adjustment.
3-30. T2 PLATE LEVEL TEST AND
ADJUSTMENT
a. Purpose. The purpose of the plate level adjustment is
to make the vertical axis of the theodolite truly vertical when
the bubble of the plate level is centered in its vial.
3-21
FM 6-2
b. Test. The plate level adjustment test for the T2 theodolite
is the same as that for the T16 theodolite. See paragraph
3-13 for the steps in this test.
c. Adjustment. To adjust the plate level, use the adjusting
pin from the accessory case. Insert the adjusting pin into
the hole of the capstan screw, and remove one-half of the
apparent error (actual error) by turning the capstan adjusting
screw. The capstan adjusting screw is located on the lower
portion of the large standard of the T2 theodolite, directly
below the collimation level bubble reflector. (See Figure
3-28.) After adjusting, repeat the plate level test to detect
and adjust for any error remaining in the plate level bubble.
The plate level is in proper adjustment when the bubble
remains centered throughout 6,400 mils rotation.
Figure 3-28. Location of plate level adjusting screw
b. Test.
Step 1. To test the optical plumb, set up the theodolite
over a station that is clearly marked by a cross or other
well-defined point.
Step 2. Suspend the plumb bob from the instrument.
Move the instrument until the plumb bob is suspended
directly over the well-defined point. Accurately level
the instrument.
Step 3. Remove the plumb bob from the instrument,
and check to ensure that the instrument is accurately
leveled (that the vertical axis is truly vertical). Look
into the eyepiece of the optical plumb. If it is in correct
adjustment, the mark on the ground will be centered in
the reticle.
c. Adjustment. If the point on the ground is not centered
in the optical plumb reticle, center the point by using the
three adjusting screws located near the optical plumb
eyepiece. Two of these adjusting screws are on opposite
sides of the eyepiece, and the third adjusting screw is below
the eyepiece. The bottom adjusting screw is locked in place
by a check nut, which is located immediately above the
head of the adjusting screw. (See Figure 3-29.)
Figure 3-29. Location of adjusting screws for optical
plumb adjustment
3-31. T2 OPTICAL PLUMB TEST AND
ADJUSTMENT
a. Purpose. The purpose of the optical plumb adjustment
is to make the vertical axis of the theodolite pass through
the station mark when the theodolite is properly leveled and
plumbed.
3-22
Step 1. With an adjusting pin, loosen the check nut.
Raise or lower the reticle by turning the bottom adjusting
screw to move the reticle image along the axis of the
optical plumb in the same direction that the screw travels.
FM 6-2
Step 2. Use two adjusting screws on each side of the
eyepiece to move the image of the reticle in the opposite
direction that the screws travel. If it is necessary to
use these screws, they should be rotated an equal
amount in opposite directions. It is usually necessary
to loosen the screw below the eyepiece slightly to adjust
the screws on the side.
Figure 3-30. Location of adjusting screws for
verticality adjustment
Step 3. When the adjusting is complete, the two
opposed adjusting screws must be fairly tight. Lock
the bottom adjusting screw in place by tightening the
check nut.
3-32. T2 VERTICALITY TEST AND
ADJUSTMENT
a. Purpose. The purpose of the verticality adjustment is
to make the vertical crossline of the reticle lie in a plane
that is perpendicular to the horizontal axis of the telescope.
Note. The newer model T2 theodolites (64 series or
newer) require no verticality adjustment at the operator
or organizational maintenance level.
b. Test.
Step 1. To teat the verticality of the vertical crossline,
select a well-defined distant point as near the horizontal
plane of the instrument as possible. Center the vertical
crossline on the selected point.
Step 2. Elevate and depress the telescope by using the
vertical tangent screw. If the vertical crossline does not
continuously track on the point as the telescope is elevated
and depressed, an adjustment is necessary.
c .Adjustment. To adjust the vertical crossline and make
it truly vertical, use the three adjusting screws on the enlarged
portion of the telescope housing between the eyepiece and
the knurled focus ring. The two screws on the right side
are slant screws (Figure 3-30), which change the vertical
position of the crossline. Loosen one slant screw and tighten
the other one an equal amount to adjust the verticality of
the crossline. The adjusting screw on the left side moves
the crossline horizontally.
3-33. T2 HORIZONTAL COLLIMATION
TEST AND ADJUSTMENT
a. Purpose. The purpose of the horizontal collimation
adjustment is to make the line of sight perpendicular to the
horizontal axis of the telescope.
b. Test.
Step 1. To test the horizontal collimation, select a
well-defined point at least 100 meters from the
instrument and at about the same height as the
instrument.
Step 2. With the telescope in the direct position, center
the vertical crossline on the selected point and read
the horizontal circle reading to the recorder. For
illustration purposes, assume your direct reading is
0000.202 mil.
Step 3. Plunge the telescope to the reverse position,
and take a reverse reading to the same point. Assume
the reverse reading is 3,200.802 mils.
Note. Only one set of direct and reverse readings is
required for horizontal collimation. Be very careful,
therefore, to prevent pointing and reading errors.
Step 4. The difference between the direct and reverse
readings should be exactly 3,200 mils. Assuming you
do not make any error in the pointings or readings,
the discrepancy between the actual difference in the
two readings and 3,200 mils is the apparent horizontal
collimation error, or twice the actual horizontal
If the apparent horizontal
collimation error.
collimation error exceeds the initial circle setting
(0000.150 mil for the T2), you should perform the
horizontal collimation adjustment.
3-23
FM 6-2
Direct reading to
selected point
EXAMPLE
0000.202
Reverse reading to the
same point (3200.802-3200)
0000.802
Spread
(0000.802 - 0000.202)
0.600 mil
Apparent horizontal
collimation error (0.600 mil + 2)
0.300 mil
Note. It is referred that the adjustment be made with
the theodolite in the reverse position. This adjustment
also can be made with the telescope in the direct
position by using the mean value for the direct pointing
(000.202 + 0.300 = 0000.502).
3-34. T2 VERTICAL COLLIMATION TEST
AND ADJUSTMENT
a. Purpose. The purpose of the vertical collimation
adjustment is to make the line of sight horizontal when the
vertical circle reads 1,600 mils with the telescope in the
direct position (4,800 mils with the telescope in the reverse
position) and the ends of the collimation level bubble aligned.
b. Test.
c. Adjustment.
Step 1. With the telescope on the point in the reverse
position, set the mean value of the direct and reverse
pointings (reverse= 3200.502) on the micrometer scale
by using the coincidence knob.
Step 2. Bring the main scale into coincidence by using
the horizontal tangent screw. This moves the vertical
crossline of the telescope off the point by the amount
of the actual horizontal collimation error.
Step 3. You must align the vertical crossline on the
selected point by lateral movement of the reticle within
the telescope. Newer models of the T2 have two
pull-action capstan adjusting screws arranged
horizontally and on opposite sides of the telescope.
To align the vertical crossline, loosen one screw and
tighten the opposite one an equal amount. The
crossline will move laterally toward the screw that you
tighten. Do not try to make the entire adjustment in
one step. Loosen and tighten the opposite screws in
small amounts. Proceed in this reamer until the
crossline is aligned on the station.
Note. On the older-model T2 (63 series or older), the
adjusting screws are those used for verticality
adjustment. To move the vertical crossline, loosen
(tighten) the two adjusting slant screws on the right
side of the telescope equally, and tighten (loosen) the
single adjusting screw on the left side of the telescope.
The adjusting screw or screws on one side of the
telescope must be loosened before you tighten the
screw or screws on the opposite side. Continue the
lateral movement of the vertical crossline until it is
aligned precisely on the selected point.
Step 4. Perform the test again, and make additional
adjustments until the difference between the direct and
reverse pointings is less than 0.050 mil.
3-24
Step 1. To test the vertical collimation, select a
well-defined point at least 100 meters from the
instrument and approximately on a horizontal plane
with the theodolite.
Step 2. With the telescope in the direct position give
the recorder a direct vertical circle reading to the point.
Be sure that the collimation level bubble is precisely
aligned.
Step 3. Plunge the telescope to the reverse position,
and give the recorder a reverse vertical circle reading
to the same point. Ensure the collimation level bubble
is precisely aligned before you read the vertical circle,
and check it after you take your reading.
Note. The T2 adjustment for vertical collimation
requires only one set of direct and reverse readings.
Be very careful, therefore, to prevent pointing and
reading errors.
c. Adjustment. The sum of the direct and reverse readings
should be 6,400 mils. Any difference between the sum of
the two readings and 6,400 mils is the apparent vertical
collimation error, or twice the actual error. If the difference
exceeds 0.150 mil for the T2 theodolite, the vertical
collimation level should be adjusted.
Step 1. With the telescope in the reverse position and
accurately sighted on the selected point, use the
coincidence knob to set the fractional part of the
corrected reading on the micrometer scale. The
corrected reading is the reverse reading with one-half
of the apparent error (actual error) applied. Then apply
the actual error to determine the corrected vertical
reading. In the example below, the actual error must
be added. So, add 0.100 mil to 4,804.607 mils to
determine the corrected reading of 4,808.707 mils. Set
the fractional part of the corrected reading (0.707 mil)
on the micrometer scale by using the coincidence knob.
FM 6-2
Direct reading
Reverse reading
Sum
Apparent error
(6400 - 6399.800)
Actual error
(0.200 + 2)
EXAMPLE
1595.193
4804.607
6399.800
0.200 mil
0.100 mil
Note. If the sum of the two readings was greater than
6,400 mils, then the actual error would be subtracted
from the reverse reading to determine the corrected
vertical reading.
Step 2. Obtain coincidence on the main scale at the
correct vertical reading by using the collimation level
tangent screw. With the telescope sighted at the selected
point and the corrected reading on the vertical scale,
the collimation level bubble will not be aligned.
Step 3. Align the images of the ends of the collimation
level bubble by rotating the two capstan adjusting
screws located directly below and to the right and left
of the collimation level mirror (prism). Adjust the
bubble images by loosening one adjusting screw and
tightening the other by an equal amount. Figure 3-31
shows the location of the adjusting screws. Continue
the test and adjustment procedures until the vertical
collimation error is lesS than 0.050 mil.
Figure 3-31. Location of adjusting screws for
vertical collimation adjustment
3-25
FM 6-2
Note. It is preferred that the adjustment be made with
the theodolite in the reverse position. This adjustment
also can be made with the telescope in the direct
position by using the corrected direct reading to adjust
the instrument; that is, 1595.293 (1595.1 93 + 0.100).
CAUTION
It may be difficult for you to remember where the
various adjusting screws are located when you need
to make adjustments on the theodolite. You should
always refer to the technical manual published for
each type of theodolite. Always perform the tests and
adjustments in the sequence in which they are listed.
After you make an adjustment, perform the test again
to check for accuracy before you go to the next test
and adjustment When making adjustments, do not
force the movement of the adjusting screws or exert
too much pressure. The screws could be damaged
and make your instrument unserviceable. A correctly
adjusted theodolite is essential in obtaining accurate
survey results.
3-26
FM 6-2
CHAPTER 4
FIELD NOTES
The field notes of any survey are the only original record of the survey that
the survey party has once it leaves the field. Therefore, the field notebook
must contain a complete record of all measurements made or determined
during the progress of the survey. It should include complete sketches,
descriptions, and remarks, when necessary, to clarify the notes. The best
survey fieldwork is of no value to the using unit if the notes are not accurate,
legible, and complete in every detail.
Note. The acronyms and abbreviations in Figure 4-1
are used In the example field notes shown in Figures
4-2 through 4-21.
4-1. FIELD NOTEBOOK
The field notebook (DA Form 4446 [Level, Transit, and
General Survey Record Book]) is a hardback, permanently
bound book for recording all survey data determined in the
field. On the flyleaf inside the front of the book are
instructions to the finder for the return of the book if it is
lost. Also on the flyleaf are spaces for the identification of
the notebook. (See Figure 4-2.) Each set of two facing pages
constitutes one numbered page. The page number appears
in the upper right comer. The first two facing pages are
reserved for the index of the contents of the notebook. (See
Figure 4-3.) The index should be kept current at all times.
Figure 4-1. Field notes acronyms and abbreviations
appmx
asst
astro alt
arty
az
az mk
BC
bldg
blvd
bn
bn SCP
BRP
cal
ck
cont
COP
EOL
E
el
FSTK
GAZ
angle
approximately
assistant
astronomic observation (attitude method)
artillery
azimuth
azimuth mark
battery center
building
boulevard
battalion
battalion survey control point
boresight reference point
caliber
check
continue
chief of party
end of orienting line
east
elevation
far stake (radar OS)
grid azimuth
H
HI
horiz
HT
hwy
ID
inst
IO
lat
long
mal
mt
N
no
1
01
02
obsr
oper
OP
0S
PAE
height
height of instrument
horizontal
height of target
highway
identification
instrument
instrument operator
Iatitude
longitude
malfunction
mountain
north
number
theodolite marks (PADS)
observation post (or observer 1)
observation post ( or observer 2)
observer
operator
observation post
orienting station
position, azimuth, elevation (PADS)
4-1
FM 6-2
Figure 4-1. Field notes acronyms and abbreviations (continued)
pos
R
rcdr
rd
recip
RP
S
SIMO
sph
sta
SW
T
TAZ
position
reverse
recorder
road
reciprocal
registration point
south
simultaneous observation
spheroid
station
southwest
telescope
true azimuth
temp
tgt
theod
TS
2
2E2
updt
U/A
vert
w/
W
WT
Z-VEL
temperature
target
theodolite
traverse station
plumb bob marks (PADS)
azimuth error (PADS)
update(d)
unadjusted/adjusted data (PADS)
vertical
with
west
water tower
zero velocity (PADS)
Figure 4-2. Example of data on flyleaf of a field notebook
4-2
FM 6-2
4-2. DATA RECORDED
a. Recorded field notes consist of a combination of tabulated
data, sketches, and descriptions. The total record of any
survey in the field notebook should provide a clear and
concise picture of the survey performed. This information
will include descriptions of the starting and closing stations,
a description of any principal station established, the area or
locality in which the work is performed, the purpose of the
survey, and general remarks on weather, terrain, or other
conditions that may be factors in evacuating the results. The
information in the field notes must be complete enough that
anyone not familiar with that particular survey operation can
take the notebook, return to the locality, and recover or
reconstruct any portion of the survey. Figures 4-3 through
4-21 are examples of common types of field notes kept by the
recorder.
b. Data are recorded in the field notebook in tabulated
columns according to a prescribed plan. Enough spaces are
provided to permit entry of mean values as they are
determined by the recorder.
c. Sketches must be made when needed. For example, if the
description of an SCP in the trig list is vague, incorrect, or
missing or if maps of the area contain errors, a sketch is
required. Each sketch should be drawn to an approximate
scale and include a grid north line. Important details of the
sketch may be exaggerated for clarity. Sketches should show
distances to at least two reference marks from any principal
station that might be buried underground. Reference marks
should be permanent in nature. If permanent reference marks
are not available, the survey party should emplace
semipermanent marks. Sketches also are used when
necessary to indicate heights of survey signals and other
points when vertical angles are observed to other than
instrument height. A small protractor, which can also be used
as a straightedge, should be used as an aid in making sketches.
Each sketch should be legible and should be drawn large
enough to ensure that it can be understood. Each station
shown on the sketch should be identified.
d. Description should be used to supplement the information
shown in the sketch. Remarks may be made to clarify
measurements, weather, terrain, and observing conditions.
The remarks should include any other factors that might be of
any value in the evaluation of the survey. Approved
abbreviations and conventional symbols will be used on
sketches and in descriptions.
Figure 4-3. Example index of a field notebook
4-3
FM 6-2
4-3. RECORDING
a. Each numbered page of the field notebook provides space
for recording information pertinent to the survey. The type of
survey (traverse, resection, and so forth) and the date are
entered at the top of the left side of the page. Weather
conditions (two variables that identify visibility and
temperature), the type and serial number of the instrument,
and the names of the party personnel are entered across the
top of the right side of the first page of each survey. The rest
of the pages are used for recording survey data (instrument
readings, mean angles, and distances); for designating the
survey stations; for recording telescope positions or number
of repetitions measured; and for recording remarks, sketches,
and descriptions. The chief of party will check data entered
on each page and initial each numbered page before leaving
the field. (If an incorrect angle or distance is discovered, it can
be remeasured before the party leaves the area.) The
instrument operator also should check recorded values for
each occupied station before taking down the instrument.
b. All entries in the field notebook will be printed in capital
block letters and in a neat and legible manner. Always use a
sharpened pencil with lead soft enough to be readily seen but
hard enough to be smear proof (3H or harder). Entries will
never be made in ink. The recorder goes with the instrument
operator and records the data in the field notebook as they are
announced to him. He then reads data back to the instrument
operator to ensure his entry is correct. Field data entries are
recorded directly in the field notebook and not on scraps of
paper for later transfer. As the entries are made, the recorder
computes and records mean values and, for ease of
identification, encircles the data that will be used to compute
the survey. The recorder will immediately notify the
instrument operator of any incorrect angle before the
instrument is moved from the station. Station descriptions,
sketches, and remarks are entered in the notebook before the
survey party moves to the next station and must be complete
enough to permit reestablishment. Only the data for that
specific survey will be recorded on the page. Data pertaining
to surveys other than the one in progress will be recorded on
other pages.
c. Erasures are not permitted in the field notebook. If an
incorrect entry is made, it is corrected by drawing a single line
through the incorrect data and entering the correct data
directly above the incorrect data. When a page is filled with
data, sketches, or remarks that will not be used because of a
change in plans, the page is crossed out by drawing diagonal
lines between opposite comers of each side of the page and
printing the word VOID in large letters across each side of the
page. (See Figure 4-20.) Figure 4-19 is an example of a
partially voided page on which all other recorded data are
correct.
Figure 4-4. PADS notes
4-4
FM 6-2
4-4. TYPES OF FIELD NOTES
Procedures covering all situations cannot be prescribed;
therefore, the examples in Figures 4-2 through 4-21 should
be used as a guide in developing suitable techniques, PADS
data will also be recorded in DA Form 4446. In the heading,
enter the designation of the type of survey performed (PADS
survey). The date will be the actual date of the PADS survey.
In the heading of the adjoining page, show the PADS serial
number (electrical mounting base), the spheroid number, and
the total mission time. Across from these three items, enter
the names of the PADS operator, assistant operator, and the
Z-VEL time used to conduct the mission. Label the columns
below the heading, from left to right, as follows:
Ž STA—to identify the updated or marked stations.
Ž ID NO—to identify the storage position in the PADS
computer corresponding to the update or marked
stations. The PADS can store up to 30 positions.
Ž PAE–to identify the function performed at each
position.
Ž U/A—to identify unadjusted or adjusted data.
Ž EASTING–to identify the universal transverse
mercator (UTM) grid zone and casting grid of the
position.
Figure 4-5. PADS notes (continued)
4-5
FM 6-2
Ž NORTHING—to identify the northing grid of the
position.
Ž EL-to identify the elevation of the position.
Ž TAZ-GAZ–to identify the true azimuth and grid
azimuth of a plumb bob two-position azimuth mark.
Ž DISTANCE-to identify the distance (in meters) from
the last marked position, when required, or the distance
measured in an optical measurement.
Ž MALFUNCTION–to identify any malfunctions
during the survey mission.
Note. Use the next recording page for recording
horizontal an angIes, grid azimuth, and offset distances
for all optics measurements performed during the
survey. The rest of the page will be used for remarks.
4-5. SECURITY OF FIELD NOTES
A field survey notebook is as valuable 10 the enemy as a
captured map. The notebook would enable the enemy to
locate battery centers, OPs, and other military assets (radars,
mortars, and such). For this reason, every effort must be
made to safeguard the notebook.
Figure 4-6. Traverse (1:1,000) notes
4-6
FM 6-2
Figure 4-7. Traverse (1:1,000) notes (continued)
Figure 4-8. Triangulation (1:1,000) notes
4-7
FM 6-2
Figure 4-9. Triangulation (1:3,000) first position notes (two-position angle measurement)
Figure 4-10. Triangulation (1:3,000) second position notes (two-position angle measurement) (continued)
4-8
FM 6-2
Figure 4-11. Three-point resection notes
Figure 4-12. Trig-traverse notes
4-9
FM 6-2
Figure 4-13. Astro altitude method notes (sun or star)
Figure 4-14. Artillery astro notes (sun or star)
4-10
FM 6-2
Figure 4-15. Azimuth determination with SIAGL
Figure 4-16. Hasty astro observation notes (sun or star)
4-11
FM 6-2
Figure 4-17. Simultaneous observation, master station notes
Figure 4-18. Simultaneous observation, flank station notes
4-12
FM 6-2
Figure 4-19. Example of partially voided page notes
Figure 4-20. Example of a voided page
4-13
FM 6-2
Figure 4-21. Polaris tabular method notes
4-14
FM 6-2
CHAPTER 5
TRAVERSE
In survey, traverse is defined as the field operation of measuring the
lengths and directions of a series of straight lines connecting a series of
points on the earth. Each of these straight lines is called a traverse leg,
and each point is called a traverse station.
Section I
METHODS AND PROCEDURES
Traverse legs are measured by using electronic devices, a 30-meter steel tape, or trig-traverse
procedures. At each traverse station, a horizontal angle is measured and used to determine the
azimuth of the next traverse leg. These measurements are used to compute the relative horizontal
position of each unknown traverse station on some system of coordinates, such as the UTM grid
system. A vertical angle is also measured at each station and is used to determine the height
above or below vertical datum of each of the unknown traverse stations. In FA surveys, the
angular measurements may be made with one of two instruments, depending on the accuracy
required and the echelon at which the traverse is conducted. These instruments are the T16 and
T2 theodolites.
5-1. FIELDWORK
In a traverse, three stations are considered to be of immediate
significance. (See Figure 5-l.) These stations are referred
to as the rear station, the occupied station, and the forward
station. The rear station is that station from which the persons
performing the traverse have just moved or a point to which
the azimuth is known. The occupied station is the station
at which the angle-measuring instrument is set up. The
forward station is the next station in succession and is the
immediate destination of the party. During the traverse
(Figure 5-2), the horizontal angles, vertical angles, and
distances are measured.
successive stations in a traverse exceeds 1,000 meters, the
vertical angle must be measured reciprocally (measured from
each end of that particular traverse leg). This reciprocal
measurement procedure is used to eliminate errors caused
by curvature and reflection. Vertical angles are used in
determining the difference in height between stations.
Figure 5-1. Stations of immediate significance
a. Horizontal Angles. Horizontal angles are determined
from instrument readings made at the occupied station by
sighting the instrument on the rear station and turning the
instrument clockwise to the forward station. When
measuring horizontal angles, the instrument is always sighted
at the lowest visible point of the station markers designated
the rear and forward stations. Horizontal angles are used
in determining azimuths.
b. Vertical Angles. Vertical angles are determined from
instrument readings made at the occupied station to the height
of instrument on the station marker (usually a range pole)
at the forward station. When the distance between two
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Figure 5-2. Diagram of a traverse
c. Distance. The distance between the occupied station and
the forward station is measured by using electronic devices,
horizontal taping, or trig-traverse procedures (see Section
IV). The distance is used in conjunction with the horizontal
and vertical angles to determine coordinates and height.
5-2. STARTING CONTROL (TRAVERSE
REQUIREMENTS)
The purpose of traverse is to locate the unknown points
relative to each other and to locate all points within the
traverse relative to a common grid. Three elements of starting
data are needed. They are the coordinates and height of a
starting point and an azimuth to a visible azimuth mark.
(See Figure 5-3.) Starting data may be obtained from existing
control data or maps or may be assumed.
a. Known Control. Known survey control data may be
acquired from trig lists, local or national survey agencies,
or supporting survey elements of a higher HQ. An azimuth
to an azimuth mark (starting direction) may be obtained by
use of a SIAGL by astronomic observation, by computation
from known coordinates, by reference to an existing trig
list, and by PADS.
Figure 5-3. Diagram of a traverse with starting data
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b. Maps. If no known control is available, a careful map
inspection may be used to determine starting coordinates
and height. For survey purposes, data scaled from a map
are considered to be assumed data. If possible, a starting
azimuth should be determined by using a SIAGL astronomic
observation, simultaneous observation or PADS. If the
situation is such that none of these methods can be used,
then a starting azimuth maybe obtained by carefully scaling
from a large-scale map or by using a declinated compass.
c. Assumed. When neither known control nor maps are
available, the coordinates and height for the starting station
may be assumed. Starting direction will be determined by
the most accurate means available. Assumed data must be
converted as soon as more accurate starting control becomes
available.
5-3. TYPES OF TRAVERSE
There are three types of traverse used in FA survey. These
are open traverse, closed traverse, and directional traverse.
a. Open Traverse. An open traverse begins at a point of
known control and ends at a station whose relative position
is known only by computations. The open traverse is
considered to be the least desirable type of traverse, because
it provides no check on the accuracy of the starting control
or the accuracy of the fieldwork. For this reason, traverse
is never deliberately left open. Open traverse is used only
when time or enemy situation does not permit closure on
a known point.
b. Closed Traverse. This traverse starts and ends at stations
of known control.
There are two types of closed
traverse–closed on the starting point and closed on a second
known point.
(1) Closed on the starting point. This type of closed
traverse begins at a point of known control, moves through
the various required unknown points, and returns to the same
point. This type of closed traverse is considered to be the
second best and is used when both time for survey and
limited survey control are considerations. It provides checks
on fieldwork and computations and provides a basis for
comparison to determine the accuracy of the work performed.
This type of traverse does not provide a check on the accuracy
of the starting data or ensure detection of any systematic
errors. If a conventional survey team uses a PADS SCP,
they must close on the same point because of the PADS
circular error probable (CEP) and errors in determining
assumed data.
(2) Closed on a second known point. This type of closed
traverse begins from a point of known control, moves through
the various required unknown points, and then ends at a
second point of known control. The point on which the
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survey is closed must be a point established to an equal or
higher order of accuracy than that of the starting point. This
is the preferred type of traverse. It provides checks on
fieldwork, computations, and starting control. It also
provides a basis for comparison to determine the accuracy
of the work performed.
of markers may be used, such as shell casings or concrete
monuments.
Figure 5-4. Survey station marked with a
reference stake
c. Directional Traverse. Directional traverse is a type of
traverse that extends directional control (azimuth) only. This
type of traverse can be either open or closed. If open, the
traverse should be closed at the earliest opportunity. It can
be closed on either the starting azimuth or another known
azimuth of equal or higher order of accuracy. It also can
be closed by comparison to an astronomic azimuth,
gyroscopic azimuth, or a PADS azimuth. Since direction
is the most critical element of FA survey and time is frequently
an important consideration it is sometimes necessary at lower
echelons to map-spot battery locations and extend direction
only.
5-4. TRAVERSE STATIONS
a. Selection of Stations. In FA survey, sites for traverse
stations normally are selected as the traverse progresses.
Stations must be located so that at any one station both the
rear and forward stations are visible. Some brush cutting
may be required to clear lines of sight between stations. If
the distance is to be measured with a tape, the line between
stations must be free of obstacles for the taping team.
Electronic lines of sight must also be free of obstructions
if electronic equipment is to be used. The number of stations
in a traverse should be kept to a minimum to reduce the
accumulation of instrumental errors and the amount of
computation required. Short traverse legs require the
establishment and use of more stations and may cause
excessive errors in azimuth because small errors in instrument
centering and pointings will be magnified and reflected in
the azimuth closure.
b. Station Markers. Traverse station markers are
usually l-inch by l-inch wooden stakes, 6 inches or more
in length. These stakes, called hubs, are driven flush with
the ground. The center of the top of the hub is marked
with a surveyor’s tack or with an X to designate the exact
point of reference for angular and linear measurements. To
help in recovering principal stations such as the OS, EOL,
and north reference point and its azimuth mark (patriot unit),
a reference (witness) stake is driven into the ground so that
it slopes toward the station. (See Figure 5-4.) The
identification of the station is written on the reference stake
with a lumber crayon or china-marking pencil or on a tag
attached to the stake. Signal cloth may also be tied to the
reference stake to further help in identifying or recovering
the station (unit standing operating procedure [SOP]).
During phases of survey expansion, more permanent types
5-4
c. Station Signals. Signals must be erected over survey
stations to provide sighting points for the instrument operator
and to serve as a reference for tape alignment by the taping
team. Permanent tripods or similar signals have been erected
over some primary survey control stations so that the stations
can be occupied without disturbing the signal. In artillery
survey, most of the station sites are selected and marked as
the fieldwork progresses. Temporary signals must be erected
at the stations as they are needed. The equipment used for
station signals is discussed below.
(1) Range poles. Range poles are made of tubular steel,
and each consists of two interlocking sections. The
assembled pole is 6.5 feet long, and one end is tapered to
a point. The pole is painted in l-foot sections with alternate
colors of red and white. For storage, the pole is disassembled
and placed in a canvas case. To use the range pole, place
the tapered point on the station mark and use a rod level
to make the pole vertical for observations. Place the angular
portion of the level against the pole, with the circular level
vial facing upward. Then move the top of the pole until
the bubble in the vial is centered. Check the verticality of
the range pole by verifying that the bubble remains centered
at other points on the range pole. Maintain the range pole
in a vertical position throughout the observing period,
normally by using a range pole tripod. To prevent the
measurement of angles to the wrong point, place the range
pole in a vertical position only when it is being used to
mark a survey station. Cloth flags of various colors may
be attached to the top of the range pole to help identify the
station.
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(2) Target set, surveying. To mark survey stations,
artillery missile batteries that have special accuracy
requirements for the azimuth of the orienting line use the
target set. (See Figure 5-5.) The target set may also be
issued to FA survey elements that are required to perform
survey to fourth-order accuracy. The target is mounted on
the same tripod that is used with the T2 and T16 theodolites.
The tripod is set up, leveled, and plumbed in the same manner
as the theodolite tripod. After setup, the target is oriented
so that it can be seen directly by the instrument that is
sighting on it. The target can be illuminated for night use.
Greater accuracy is obtained on short traverse legs by using
the target rather than range poles. When the telescope is
sighted on the target, the telescope cross hairs should bisect
the triangles of the target. Flexibility can be obtained by
interchanging and leapfrogging theodolites and targets. This
reduces setup time by leaving tripods and tribrachs in place.
The target level and optical plumb on the target must be
adjusted in the same manner as for the T2 theodolite.
Figure 5-5. Tripod-mounted target
5-5. ORGANIZATION OF
CONVENTIONAL TRAVERSE
PARTIES
The number of personnel authorized to perform survey will
depend on the unit TOE. The organization of these persons
into a traverse party and the duties assigned to each member
will depend on the unit SOP. The organization and duties
of traverse party members and modifications proposed for
reduced-strength parties (a through d below) are based on
the functional requirements of a traverse. See Chapter 1
for a detailed description of individual duties.
5-5
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a. Fifth-Order Traverse Party.
(1) Chief of party. The chief of party plans the traverse,
selects and marks the locations of the traverse stations, and
supervises the work of the other members of the party. When
directed, he helps the survey officer or chief surveyor in
the reconnaissance and planning of the survey.
(2) Instrument operator. The instrument operator
measures the horizontal and vertical angles at each traverse
station. He measures distances with the SEDME-MR. He
also operates the azimuth gyro and is responsible for the
care and cleaning of those instruments.
(3) Computer-recorder. The computer-recorder keeps
the field note-s for the party in a field notebook. He records
the angles measured by the instrument operator, the distances
measured with the SEDME or measured by the tapemen,
and all other data pertaining to the survey. He also checks
the length of each taped traverse leg by pacing (fifth order).
Also, he computes the grid coordinates and height of each
traverse station as the traverse progresses and checks his
results with the computer.
instruments. When the 30-meter steel tape is used, the
rodman-tapeman and an individual designated by the chief
of party measure the distance from one traverse station to
the next. Each keeps a record of the distance taped. They
compare their recorded distances before reporting the
measured distance to the recorder. The rodman-tapeman
maintains all taping equipment.
b. Fourth-Order SEDME Traverse Party. The fourthorder SEDME traverse party is equipped with two T2
theodolites and one SEDME-MR. The personnel are one
chief of party, twoinstrument operators, two
computer-recorders, and one rodman. Party deployment and
measuring operations are shown in Figure 5-6. Measuring
Section (MS) 1 occupies the survey control point, measures
Angle 1 (A1), and sets up a set of infrared reflectors (IRRs)
before moving to TS 2. Measuring Section 2 occupies TS
1, measures A2 and distances 1 and 2 (D1 and D2), and
moves to TS 3 to repeat the cycle. The recon section plans
the survey, establishes forward stations, and recovers the
IRRs and range poles, as required.
c. Fourth-Order Taped Traverse Party. Duties for a
fourth-order taped traverse are the same as in a above with
the exceptions discussed below.
(4) Computer. The computer computes the grid
coordinates, height, and azimuth of each traverse station
as the survey progresses.
The computer and the
computer-recorder work independently and check their
results with each other.
(1) The computer-recorder is not required to check the
length of a taped traverse leg by pacing.
(5) Rodman-tapeman. The rodman-tapeman helps in
setting up and marking stations. He erects the SEDME
reflector and helps the instrument operator care for the
(2) In artillery fourth-order taped traverse, all distances
are double taped to a comparative accuracy of 1:5,000. The
recorder helps the rodman-tapeman with the taping operation.
Figure 5-6. Operational concept for div arty or TAB survey party
5-6
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(3) There are two instrument operators and two T2
theodolites in each fourth-order party.
d. Reduced-Strength Party. Often, enough personnel are
not available for a full traverse party. In such circumstances,
members of the survey party may be required to do more
than one job. Shortages in personnel will never affect the
jobs of the instrument operator or tapemen, since these two
jobs must be done if a traverse is to be conducted. Shortages
will, therefore, be apparent in the duties of rodman, computer,
and computer-recorder. If the party is short one rodman,
the chief of party will perform, in addition to his own duties,
the duties of the rodman. If three or more members are
absent from the party, the fieldwork is completed and the
computations are performed later by designated personnel.
The organization of a reduced-strength party is not bound
by strict rules. However, for a party to function when
personel shortages exist, each party member must be trained
to perform all duties.
5-6. NIGHT TRAVERSE
At times, the FA surveyor will be required to survey at night
to accomplish his mission. Night traverse can be done by
modifying daylight techniques and organization. However,
night traverses require more work, more training, more
personnel, and more coordination.
a. Equipment. The same equipment used for performing
daylight traverse is also used to perform night traverse with
the addition of night-lighting equipment. This lighting
equipment includes flashlights for all personnel and two
signal lights for each range pole. If signal lights are not
available, two flashlights for each range pole will suffice.
All lighting devices should be equipped with filters of some
type to ensure greater light security and to prevent undue
glare in the telescope of the observing instrument when it
is pointed at a station. The observing instrument should be
equipped with its integral lighting equipment.
b. Personnel. The standard traverse party must be
supplemented with additional personnel to enable it to
function properly at night. Three additional men who are
light holders go with and help the tapemen.
c. Station Marking. At night, the traverse stations are
marked the same as in daylight except for the lighting devices
required at the rear and forward stations. Two signal lights
should be placed on each range pole that will be observed
from a traverse station. Usually, this will include two range
poles-both the rear and the forward stations. One of these
lights should be placed on the pole at the height of the
instrument and the other at the lowest point visible from
the instrument. Both lights should be pointed directly at the
observing instrument. If signal lights are not available,
flashlights may be taped or securely strapped to the pole in
the same manner prescribed for the target lights. To ensure
that the lights are placed and pointed properly, the chief of
party will designate one man to remain with the range poles
and coordinate the placement and pointing of the lights with
the instrument operator.
d. Angle Measuring and Recording.
(1) Angle measuring. There is no different between
measuring angles at night and measuring angles during
daylight, except at night the instrument must be equipped
with a night-lighting device. The chief of party should
coordinate with the instrument operator to ensure that the
lights at the rear and forward stations are placed and pointed
properly and are moved to the next station when the
observation is completed.
(2) Recording. The same recording procedures used for
recording during daylight hours are used for night recording
except that the recorder must have a flashlight so he can
see to record. He should record in the remarks section of
the field notes anything that may affect the survey, such as
burnt-out lights or only one light on the forward station.
e. Distance Measurement at Night.
(1) Taping. For information on taping at night see
paragraph 2-18.
(2) SEDME. Use the same procedures at night as for
daylight measurements. Lighting devices are required to
orient the SEDME and reflector assembly. After the SEDME
is oriented and before measurements are taken, lights at or
behind the reflector assembly must be turned off.
Communication between stations must be maintained.
f. Communication. Communication during a night traverse
should be by radio. However, radio is not always convenient
or available, and at times, the survey party must resort to
light signals. These light signals should be prearranged and
simple. For example, the instrument operator may have to
signal the rodman to raise or lower the bottom light on a
range pole or inform him to move to the next station. In
arranging signals, the survey party should avoid waving
lights, since a waving light may easily attract the enemy’s
attention. Every precaution should be taken in sending light
signals to avoid detection by the enemy.
5-7. TRAVERSE FIELD NOTES
For correct procedures and examples of field notes on
traverse, see paragraphs 4-1 through 4-5 and Figures 4-6 and
4-7.
5-7
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Section II
TRIGONOMETRY OF TRAVERSE
The distance and azimuth between points can be used to form and compute a right triangle. The
distance between points serves as the hypotenuse, and the azimuth can be used to determine an
angle. Three right triangles must be solved for each leg. Three trigonometric functions are used
to compute a traverse. These functions are the sine, cosine, and tangent. The sine and cosine
functions are used to compute the differences in casting and northing coordinates. The tangent is
used to compute the difference in height.
5-8. AZIMUTH DETERMINATION
An azimuth to an azimuth mark (starting direction) may be
obtained by use of the following:
Ž SIAGL.
Ž Astronomic observation.
Ž Amputation from known coordinates.
Ž Reference to an existing trig list.
Ž PADS.
As the last effort, the azimuth maybe scaled from a map, but
an accurate azimuth must be obtained as soon as possible.
5-10. AZIMUTH AND DISTANCE
COMPUTATIONS
In survey operations, the azimuth and distance between two
stations of known coordinates must be determined. Some
examples of such a requirement are the computation of the
following:
Ž Azimuth and length of a target area base.
Ž Base of a triangulation scheme.
Ž Azimuth and distance between critical points inconverting
an assumed grid to a common grid.
Ž Astarting azimuth for a control point when the coordinates
of the two intervisible points are known.
5-11. DA FORM 5590-R
5-9. EXTENDING AZIMUTH
In artillery survey, direction may be defined as the angular
measurement between a specific reference line and a given
line. Azimuth is the term used in artillery survey to describe
direction and is the horizontal clockwise angle from a
reference line (grid north [GN]) to a given line. Every line
has two azimuths (a forward azimuth and a back-azimuth),
depending on the observer’s position on the line. In Figure
5-7, a survey is progressing from Station A toward Station B.
Angle a is the forward azimuth for the line from A to B. To
designate the azimuth from B to A, the Angle b is used. This
is known as the back-azimuth of the line. For artillery survey
purposes, the forward azimuth and the back-azimuth of a line
differ by 3,200 mils (forward azimuth ±3,2000 mils =
back-azimuth). To compute a traverse, an azimuth to the
forward station must be determined for each leg of the
traverse. This is done by adding the value of the station angle
to the azimuth to the rear station. Figure 5-8 and the example
on page 5-9 illustrate this procedure. It should be noted that
on occupation of each successive station, the first step is to
compute the back-azimuth of the preceding traverse leg.
5-8
DA Form 5590-R (Computation of Azimuth and/or Distance
From Coordinates (BUCS)) (Figure 5-9) is used to record the
computation of the grid azimuth and distance between two
points of known coordinates. (A reproducible copy of this
form is at the back of this book.) The form is designed to help
the operator perform the computations. The form has five
sections as discussed below.
a. At the top of the form, right below the form title, you
will notice six blocks. These blocks are for recording
administrative information. Each block is labeled for the
information required for each block. When conducting field
survey operations, all required information must be entered.
b. On the left side of the form under the six administrative
blocks, are the instructions for using the BUCS. These
instructions consist of three columns–STEP, PROMPT, and
PROCEDURE. These columns are used to compute the
azimuth and distance.
(1) The STEP column specifies the sequence in which the
computations must be performed.
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Figure 5-7. Azimuth and back-azimuth
Figure 5-8. Diagram of determination of azimuths
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(2) The PROMPT column indicates the display that
should appear on the BUCS at each step.
(3) The PROCEDURE column lists the actions that the
operator must take at each step.
c. Immediately below the INSTRUCTION section is the
REMARKS: section. The REMARKS: section is used for
recording any information that will help clarify the
computations or survey.
d. On the right side of the form under the administrative
section, is a block containing notes. The purpose of these
notes is to help the operator use the form and the BUCS
to compute the survey.
e. On the right side of the form under the notes is the DATA
RECORD section. The blocks in the DATA RECORD section
are used for recording the field data, known data and station
names. This is where the known coordinates of the occupied
station and the azimuth mark, the name of the occupied
station and the azimuth mark, and the results of the BUCS
computations are recorded. (See Table 5-1 for instructions
on computing DA Form 5590-R.)
(1) The blocks marked with a filled-in arrow are for
recording the known coordinates. Blocks that are not marked
with the filled-in arrow are for recording the computed
azimuth and distance. The remaining blocks are for recording
the station names.
(2) There are spaces on the form to record the results
of four individual sets of azimuth and distance computations.
Table 5-1. Instructions on computing DA Form 5590-R
5-10
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Figure 5-9. Sample DA Form 5590-R
5-11
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5-12. AZIMUTH AND BEARING ANGLE
RELATIONSHIP
5-13. DETERMINATION OF BEARING
ANGLE
a. An azimuth is required in traverse to permit determination
of a bearing angle. The bearing angle of a traverse leg and
not the azimuth is used in traverse computations to determine
differences in coordinates. The bearing angle of a line is
the acute angle formed by the intersection of that line with
Figure 5-10 illustrates the
a grid north-south line.
relationship between the azimuth of a line and its bearing
angle.
The manner in which the bearing angle is computed from
a given azimuth depends on the quadrant in which that
azimuth lies. (See Figure 5-11.)
b. In artillery survey, the horizontal plane (or circle) is
divided into four quartets. Each quarter circle contains 1,600
mils and is called a quadrant. The four quadrants are
numbered in a clockwise direction, since azimuths are
measured in a clockwise direction. Numbering begins at
grid north and proceeds around the circle, using reman
numerals I through IV. (See Figure 5-10.)
Figure 5-10. Azimuth-bearing relationship
5-12
a. When the azimuth is in the first quadrant (0 to 1,600
mils), the bearing angle equals the azimuth.
b. When the azimuth is in the second quadrant (1,600 to
3,200 mils), the bearing angle equals 3,200 mils minus the
azimuth.
c. When the azimuth is in the third quadrant (3,200 to 4,600
mils), the bearing angle equals the azimuth minus 3,200
mils.
d. When the azimuth is in the fourth quadrant (4,600 to
6,400 mils), the bearing angle equals 6,400 mils minus the
azimuth.
Figure 5-11. Determination of bearing angles
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5-14. TRIGONOMETRY AND THE
TRAVERSE LEG
a. If the coordinates of a point are known and the azimuth
and distance from that point to a second point are known,
the coordinates of the second point can be determined. In
Figure 5-12, the coordinates of Station A are known and
the coordinate of TS 1 are to be determined. The azimuth
and distance from Station A to TS 1 have been determined
by turning the horizontal angle at Station A from the azimuth
mark to TS 1 and by measuring the horizontal distance from
Station A to TS 1.
b. Determining the coordinates of TS 1 requires the solution
of a right triangle. The intersection of the north-south line
through Station A and the east-west line through TS 1 forms
a right angle (1,600 mils or 900). The known side (A to
TS 1) (measured distance) becomes the hypotenuse, and the
bearing angle at Station A is determined from the azimuth
of Station A to TS 1. Thus, a right triangle is formed.
5-15. COORDINATE COMPUTATIONS
The two unknown sides of this right triangle are designated
as the difference in casting (dE) and the difference in northing
(dN). To compute the length of sides dE and dN, use two
of the trigonometric functions of a right triangle. To
determine dE, use the following formula:
Sine of bearing angle
dE
opposite side
distance
hypotenuse
dE = sine of bearing angle x distance
Note. When using a BUCS or a calculator capable of
performing logarithms, enter the formula as follows:
Distance (Hypotenuse) x SIN (bearing angle x .05625)
END LINE = dE
To determine dN, use the following formula:
Cosine of bearing angle
dN
Adjacent side
distance
hypotenuse
or
dN = cosine of bearing angle x distance
Note. When using a BUCS or a calculator capable of
performing logarithms, enter the formula as follows:
Distance (Hypotenuse) x COS (bearing angle x .05625)
END LINE = dN
Figure 5-12. Schematic diagram illustrating dE and dN requirements
5-13
FM 6-2
To determine the coodinates of the unknown point (TS 1),
algebraically add the difference in casting to the casting
coordinate of the known point (Station A) and the difference
in northing to the northing coordinate of the known point
(Station A). In Figure 5-13, for the traverse leg appearing
in the first quadrant, the dE and dN must be added to the
casting and northing coordinates of Station A. For the
traverse legs in the other quadrants, the signs of the dE and
dN change. In all instances, the quadrant in which the traverse
leg lies determines if dE and dN are added to or subtracted
from coordinates of Station A. (See Figure 5-13.)
5-16. DETERMINATION OF dH
a. In a traverse, the FA surveyor must determine the height
of each of the unknown stations in relation to the height of
the starting (known) station. He does this by computing
the difference in height (dH) between the occupied station
and the forward station. Through the solution of a right
triangle, the vertical angle at the occupied station and the
measured horizontal distance to the forward station are used
to determine the difference in height between the two stations.
This difference is then added to or subtracted from the known
height at the occupied station.
b. In Figure 5-14, the measure distance is the horizontal
distance from Station A to Station B. The vertical angle
at Station A is measured to the height of instrument at Station
B (AA is the height of instrument at Station A, and BB is
the height of instrument at Station B). Both of the heights
are the distance from the known ground elevation at Station
A to the horizontal axis of the telescope of the instrument
being used. AA’ is equal to BB’. The height of instrument
must be determined and marked on the range pole at the
forward station. The difference in height between the two
stations is side CB of the right triangle. Determine dH as
follows :
Tangent of vertical angle =
dH
opposite side =
adjacent side
distance
or
dH = tangent of vertical angle x distance
Note. When using a BUCS or a calculator capable of
performing logarithms, enter the formula as follows:
Distance (Hypotenuse) x TAN (vertical angle x .05625) END
LINE = dH
The dH computed is actually the difference in height at
ground level between the two stations. The computed dH
is added to or subtracted from the height of the known station
according to the sign of the measured vertical angle.
Figure 5-13. Quadrant-sign relationship for dE and dN
5-14
FM 6-2
Figure 5-14. Right triangle for determination of dH
5-17. UNIVERSAL TRANSVERSE
MERCATOR GRID
The grid coordinates used most often in survey computations
are coordinates based on the UTM grid system. These
coordinates differ from the military grid reference system in
that the grid reference of a point has a grid zone designator
and a 100,000-meter square identification. The grid zone
designator and 100,000-meter identification replace the false
casting and northing digits of UTM grid coordinates. In the
lower margin of military maps, the grid reference box shows
the grid zone designator and 100,000-meter identification for
that map sheet. For a detailed discussion of map reading, see
FM 21-26, Chapter 4, page 4-17, Figure 4-14, and paragraph
4-4c(1).
5-15
FM 6-2
Section Ill
TRAVERSE COMPUTATIONS
Survey computations can be performed in any mathematical sequence that will produce the correct
solution. However, for the purpose of simplicity and uniformity, Department of the Army has
devised standardized forms for use in performing survey computations. Accurate and timely
computations are the key to a successful survey. Computations performed on a standard form are
easily checked, adjusted, and filed when necessary.
5-18. COMPUTING THE TRAVERSE LEG
a. To determine the coordinates of the unknown point, the
azimuth and distance from the known point to the first
unknown station are used.
b. Determining the coordinates of the first unknown point
requires the use of DA Form 5591-R. (See Figures 5-15
and 5-16.)
5-19. DETERMINATION OF HEIGHT
In a traverse, the FA surveyor must determine the height of
each of the unknown stations in relation to the height of the
starting (known) station. The vertical angle at the occupied
station and the measured horizontal distance to the forward
station are used to determine the height of the unknown
station.
5-20. DA FORM 5591 -R
a. DA Form 5591-R is the form on which traverse
computations are recorded. It is used in conjunction with
Program 2 (BUCS, SURVEY REV1) to determine
coordinates and height from azimuth, distance, and vertical
angle of main scheme traverse stations. The program also
converts slope distance to horizontal distance and computes
the total traverse length, total azimuth and height corrections,
radial error of closure, accuracy ratio, and traverse adjustment.
b. Entries on the form are discussed below. (Instructions
for completing the front and reverse sides of DA Form 5591-R
are in Tables 5-2 and 5-3.)
(1) The known data of the starting and closing stations
and the traverse field data are required by the BUCS. The
known starting and closing data consist of the coordinates
and height of the starting and closing stations and a line of
known azimuth at each of the stations. The traverse field
data consist of horizontal and vertical angles measured at
each station and the distance between the traverse stations.
(2) The user must enter the known starting station data
and then the traverse field data. The traverse field data
must be entered in the same sequence that the traverse stations
were encountered in the field operations.
Table 5-2. Instructions for computing DA Form 5591-R (front)
5-16
FM 6-2
Table 5-2. Instructions for computing DA Form 5591-R (front) (continued)
5-17
FM 6-2
Figure 5-15. Sample DA Form 5591-R (fifth-order traverse) (front)
5-18
FM 6-2
Table 5-3. Instructions for computing DA Form 5591-R (reverse)
5-19
FM 6-2
Table 5-3. Instructions for computing DA Form 5591-R (reverse) (continued)
(3) The operator must enter the known closing station
data to allow computation of the following:
Ž Total traverse distance.
Ž Total azimuth and height corrections.
Ž Radial error of closure.
Ž Traverse accuracy ratio.
Ž Adjusted traverse station data.
(See Figure 5-16.)
(4) The basic design of DA Form 5591-R is the same as
DA Form 5590-R. In the DATA RECORD section, there are
spaces for recording the starting data, the field data for four
traverse stations, and the computed data for three traverse
stations. The computed data for the fourth station must be
recorded on another form. Additional forms are used as
required. Closure and adjustment data are recorded on the
reverse side of the form.
(5) The administrative information is entered in the six
spaces provided on the top of each form. When a survey
operation is conducted, all information must be recorded.
(6) The names of the stations are entered in the blocks on
the left side of the DATA RECORD section. Start with the
REAR STATION: block, and then complete the STATION
NAME: blocks for the forward and known stations. Number
the known station 1. Each station name in a traverse must be
written and numbered.
(7) The coordinates of the known point are recorded in the
EASTING: and NORTHING: blocks of the DATA RECORD
section.
(8) The height of the known point is recorded in the
HEIGHT (METERS): block, The height is obtained from
a trig list of local survey control.
5-20
(9) The azimuth from the known point to an azimuth
mark is recorded in the AZIMUTH TO REAR (MILS): block.
(10) The next information recorded on the form is the
measured field data- horizontal angles, vertical angles (with
sign and whether reciprocal or nonreciprocal noted), and
the distances (whether horizontal or slope noted). The field
data must be obtained from the recorder. The recorder also
provides the station names. Enter the data in the blocks
with the black triangle.
c. The computer is now ready to compute the first leg of
the traverse.
d. The reverse side of DA Form 5591-R is used to record
the closing data for the survey just computed. The format
of the front and reverse sides of the form is similar. The
DATA RECORD section has spaces for recording the known
closing data, the measured closing horizontal angle, the
computed closing data, and the adjusted data for four stations.
Fifth-order surveys are not adjusted.
e. If the computer wishes to compute closure date, he must
record the known data of the closing station on the reverse
side of the form. He records these data as discussed below.
(1) Record the closing horizontal angle in the CLOSING
ANGLE (MILS): block. The angle is obtained from the
recorder.
(2) Record the known closing azimuth in the KNOWN
AZIMUTH FORWARD (MILS): block. This azimuth may
be determined from a trig list, by using an azimuth gym,
by astronomic observation, by computation, or by PADS.
FM 6-2
Figure 5-16. Sample DA Form 5591-R (fifth-order traverse) (reverse)
5-21
FM 6-2
(3) Record the known height in the KNOWN HEIGHT
(METERS): block the known casting in the KNOWN
EASTING: block, and the known northing in the KNOWN
NORTHING: block. These data may be obtained from a
trig list, or they could be provided by the supporting survey
element.
f. The computer ensures the BUCS is still displaying the
prompt CLOSURE (Y/N): The actions required to compute
the closing data are to press the Y key and then the END
LINE key. The BUCS now starts computing the closing
data for the survey.
5-21. RECIPROCAL MEASUREMENT OF
VERTICAL ANGLES
The effects of the curvature of the earth and atmospheric
refraction must be considered for traverse legs in excess of
1,000 meters. Vertical angles at each end of such a leg are
measured to compensate for these effects. When vertical
angles are measured reciprocally, the vertical angle at each
end of the leg should be measured to the same height above
the station (normally the HI).
5-23. RADIAL ERROR OF CLOSURE
a. The radial error of closure is determined by comparing
the correct coordinates of the closing point with the computed
coordinates of that point and determining the differences.
The difference between the two castings of the closing point,
or error in casting (eE), forms one side of a right triangle.
The difference between the two northings of the closing
point, or error in northing (eN), forms the second side of
the triangle. The hypotenuse of this right triangle is the
radial error of closure. (See Figure 5-17.) It is computed
by using DA Form 5590-R or the Pythagorean theorem.
From the Pythagorean theorem, it is derived that the radial
error of closure is equal to the square root of the sum of
the square of the error in casting and the square of the error
in northing. The equation for computing the radial error
is as follows:
Radial error of closure
5-22. ACCURACY RATlO
a. Certain minimum accuracy requirements are prescribed
for survey fieldwork and computations. These accuracies
are based on the requirements of installations to be surveyed
(howitzer position or molar position). To determine whether
this accuracy requirement has been met for a closed traverse,
an accuracy ratio is computed. If the accuracy requirement
is not met and the errors cannot be determined, the traverse
must be performed again.
b. An accuracy ratio is expressed as a ratio between the
radial error of closure and the total length of the traverse
(for example, 1:3,000, 1:1,000). It may also be expressed
as a fraction with a numerator of 1 (for example, 1/3000,
1/1000). The radial error of closure is the linear distance
between the known coordinates of the closing point and the
computed coordinates of the closing point as determined
from the survey. The total length of the traverse is the sum
of the lengths of all traverse legs (excluding distances to
offset stations). The numerator of the accuracy ratio is 1;
the denominator is equal to the total length of the traverse
divided by the radial error of closure. The equation for
the accuracy ratio is as follows:
If computed by using the BUCS, the equation is computed
as follows:
SQR(.56^2 + .72^2) END LINE = .91
Accuracy ratio =1/ total length of traverse
radial error of closure
b. The maximum allowable error in position closure for a
fourth-order traverse generally is expressed as 1:3,000, or
1 unit of radial error for each 3,000 similar units of traverse.
A maximum allowable radial error for a fourth-order survey
is determined in one of two ways. If the traverse is less
than 9,000 meters in length, the maximum allowable radial
error is determined by dividing the total length of the traverse
by 3,000. For example, in a 3,469.91-meter fourth-order
traverse, the maximum allowable radial error by the 1:3,000
evaluation is 1.15 meters (3,469.91 + 3,000). When the
traverse length exceeds 9,000 meters (9 km), the accuracy
achieved may be within 1:3,000 yet the radial error will be
excessive. Therefore, the maximum allowable radial error
(AE) is determined by the following formula:
c. After the accuracy ratio has been computed, the
denominator of the fraction is always reduced to the next
lower hundred (for example, 1/3879 becomes 1/3800).
AE
in which AE = allowable radial error and K =
total (main scheme) length of the traverse to the nearest
0.1 km.
5-22
FM 6-2
Figure 5-17. Radial error of closure
For example, using the 1:3,000 evaluation in a traverse 37.3
km in length would allow a maximum radial error of 12.4
meters (37,300 + 3,000). Whereas , would allow a
The
maximum radial error of 6.1 meters
result of the method used will then be compared with the
radial error computed for the traverse to determine if the
traverse radial error meets the requirement. The traverse
must be rerun when the radial error exceeds the computed
maximum allowable radial error and no error can be
determined.
5-24. CLOSING AZIMUTH ERROR
The closing azimuth error is determined by comparing the
known closing azimuth with the closing azimuth determined
by the traverse. The difference between the two is the closing
azimuth error. The error is considered to be within tolerance
if it does not exceed 0.1 mil per main scheme angle for
fifth-order traverse. Fourth-order traverses are evaluated for
azimuth closure in two ways. If the number of main scheme
angles is six or less, multiply the number of main scheme
angles by 0.04. For traverses of seven or more main scheme
angles, multiply the square root of the number of main scheme
angles by 0.1 (Appendix B).
5-25. ACCURACIES, SPECIFICATIONS,
AND TECHNIQUES
The overall accuracy of a traverse depends on the equipment
and methods used in the measurements, the accuracy achieved
during the fieldwork, and the accuracy of the starting and
closing data.
5-23
FM 6-2
a. Fourth-Order
fourth-order
Accuracy. Normally,
surveys are performed by the div arty survey platoon and
the TAB survey platoon to extend survey control to using
units. The maximum allowable error in position closure
for an artillery fourth-order traverse generally is expressed
as 1:3,000, or 1 unit of radial error for each 3,000 similar
units of traverse executed. A fourth-order traverse starting
from existing survey control must start and close on stations
established to fourth-order accuracy or higher. If survey
control of the required accuracy is not available, the fieldwork
and computations can be computed and the traverse evaluated
for accuracy (accuracy ratio determined) by using assumed
starting data, provided the traverse is ended at the starting
station. The T2 theodolite is used to measure the angles.
Horizontal angles are measured as one-position angles (1
D/R). Vertical readings are taken once with the telescope
in the direct position and once in the reverse position (1
D/R). The vertical angle is then computed. If traverse legs
are greater than 1,000 meters in length, vertical readings
must be observed reciprocally. Distances are double taped
with the 30-meter steel tape to a comparative accuracy of
1:5,000. When the SEDME is used, three readings must
be taken to determine the distance.
(1) Position accuracy. The procedure used to evaluate
the position accuracy of a fourth-order traverse depends on
the length of the main scheme of the traverse. Traverses
of less than 9,000 meters in main scheme length are evaluated
by determining accuracy ratios as explained in paragraph
5-23b. However, when the traverse length exceeds 9,000
meters, the accuracy achieved may be excessive. Therefore,
when the main scheme length of the traverse exceeds 9,030
meters (9 km), the maximum allowable radial error is
computed by the formula
in which K is the
total- length of the traverse to the nearest 0.1 km.
in carrying the azimuth through the traverse. If the traverse
exceeds 25 main scheme angles, then azimuth must be
checked by comparing the computed azimuth with an
astronomic azimuth, gyroscopic azimuth, a preestablished
azimuth or a PADS azimuth. The allowable azimuth error
in mils for a traverse having no more than six main scheme
angles is computed by the formula AE = 0.04 x N, in which
N is the number of main scheme angles used to carry azimuth.
If there are more than six main scheme angles in the traverse,
the allowable azimuth error is computed by the formula
AE=0.1
(3) Height accuracy. The allowable error in meters for
the height closure of a traverse of any length performed to
fourth-order accuracy is also computed by the formula
AE =
b. Fifth-Order Accuracy. NormalIy, FA battalions perform
fifth-order survey to establish survey control for the firing
units of the battalion. A fifth-order traverse starting from
existing control must start and close on stations established
to fifth-order accuracy or greater. When survey control of
the required accuracy is not available, the fieldwork and
computations can be completed and the traverse evaluated
for accuracy (accuracy ratio) by using assumed starting data,
provided the traverse is closed on the starting station. The
T16 theodolite is used to measure the angles. Horizontal
angles are turned one position with the T16 theodolite.
Vertical readings arc taken once with the telescope in the
direct position and once with the telescope in the reverse
position (1 D/R), The vertical angle is then computed.
Distances, when measured with the 30-meter steel tape, are
single taped and checked for gross errors by pacing. When
distances are measured with the SEDME, three readings will
be taken.
(1) Position accuracy. The maximum allowable error
in position closure is expressed by the accuracy ratio of
1:1,000, or 1 unit of error for each 1,000 similar units of
traverse executed.
Therefore, in this example, 3.85 meters is the maximum
allowable radial error for the traverse length. If the radial error
of the traverse exceeds 3.85 meters and no errors are
determined, the traverse must be rerun.
(2) Azimuth closure. The allowable error in azimuth
closure depends on the number of main scheme angles used
5-24
(2) Azimuth closure. The allowable error in azimuth
closure is computed by the formula AE = 0.1 mil x N, in
which N is the number of main scheme angles in the traverse
After 20 main scheme angles, azimuth must be checked by
comparing the computed azimuth with an astronomic
azimuth gyroscopic azimuth, a preestablished azimuth, or
a PADS azimuth.
(3) Height accuracy. The maximum allowable error
in height closure is 2 meters for traverses of less than 4,000
meters. For traverses over 4,000 meters, use the formula
AE = 1.2 x
to compute allowable error.
FM 6-2
Section IV
TRIG TRAVERSE
When a traverse is conducted in the field, it may be impossible to tape or electronically measure
a traverse leg because of the terrain, electrical interference, or equipment failure. If this occurs,
a method known as trig traverse may be used. When properly executed, this method is adequate
for accomplishing fourth- and fifth-order traverse requirements. The trig traverse method uses the
triangular figure, the base of which is carefully measured.
5-26. METHOD
In the trig traverse method, the base of the triangle need
not be established perpendicular to the required side of the
triangle but may be established at an angle more convenient
for measurement. When possible, however, it should be
placed perpendicular to the required side by using the
theodolite to place the base ends at right angles to the desired
side. If it is not possible to make the base perpendicular,
the angle formed by the base and the desired side must be
measured. The base must be long enough to minimize the
effects of instrumental error on the distance to be measured.
To do this, the base must be longer than one-twentieth and
preferably about one-tenth of the distance to be determined.
In Figure 5-18, the length to be determined is the line AB.
Two independent bases are measured to offset the slight
inaccuracy that will prevail in the base measurement and
to provide a check on the work. The bases are shown by
the lines BC1 and BC2. The shortest base should not be
less than one-twentieth of the required distance.
Figure 5-18. Trig traverse method
5-25
FM 6-2
5-27. BASE ACCURACY
The accuracy of the base measurement is the key to a
succesful trig traverse. When the base length is onetwentieth of the required side and an error of 0.01 meter
was made in determining the length of the base, the result
is an error of 0.20 meter in determining the computed length
of the base. Each base should be double taped separately
within a comparative accuracy of 1:7,000 for fourth order
and 1:3,000 for fifth order. The distance C1 to C2 is also
measured to provide a check. Reasonable control over the
accuracy of the distance measurements can be exercised by
limiting the ratio of the length of the base to the length to
be computed.
is the angle from B to C2, BC1 is the distance from B to
C1, and BC2 is the distance from B to C2. See the
perpendicular base in Figure 5-18.
b. Nonperpendicular Base.
When the base is not
perpendicular, the distance is computed by using the
following formulas:
Y is the angle formed by the base and the required side.
See the nonperpendicular base in Figure 5-18.
5-28. ANGLES
a. In fourth-order survey, the T2 theodolite is used for angle
measurement. Two-position horizontal angles are measured.
If the two measured values for any angle differ by more
than 0.050 mil, these angles will be rejected and remeasured.
5-31. DA FORM 5603-R
b. In fifth-order survey, the T16 theodolite is used for angle
measurement. One-position horizontal angles are measured.
Trig traverse is computed with the BUCS and by using DA
Form 5603-R (Computation of Trig Traverse/Subtense
(BUCS)), (A reproducible copy of this form is included at
the back of this book.) This form follows the same basic
format of the BUCS forms used in computing the traverse.
5-29. TARGETS
a. The top of the form is for recording administrative data.
Data in this area include the following:
Because of the very short distance to the end of the base,
the targets must be designed for accurate pointings. The
string of a suspended plumb bob or a sharpened pencil point
may be sighted on. On longer bases, a range pole may be
used, provided the range pole is very carefully plumbed
over the point. If available, a tripod-mounted target may
also be used. It also must be carefully leveled and plumbed
over the point.
Ž Computer.
Ž Name of the individual who checks the computations
(checker).
Ž Area in which survey was performed.
Ž Notebook reference.
Ž Date computations were performed.
Ž Identification of the sheet number.
5-30. DISTANCE COMPUTATION
Two independent lengths (AB1 and AB2) are computed,
one from each base. The mean of the two computed lengths
is the required distance. A comparative accuracy is computed
to determine the reliability of the computed distance. For
fourth-order survey, the required side accuracy must be at
least 1:5,000; and for fifth-order survey, at least 1:1,000.
Computations for perpendicular and nonperpendicular bases
without the use of DA forms are described below.
a. Perpendicular Base. If the base is perpendicular to the
required side, the distance is easily computed by using the
following formulas:
AB1 = cot Q1 x BC1
AB2 = cot Q2 x BC2
AB is the required distance (AB1 is the first distance, AB2
is the seared distance), Q1 is the angle from B to Cl, Q2
5-26
b. The next part of the form provides notes for the specific
operations of the program and other notes needed to complete
the form.
c. The next part of the form is divided into two major sections.
The section on the left provides instructions for the operator
to complete the program.
(1) The right section is for recording data-both field
and computed. TWO trig traverses may be computed on each
form.
(2) The left section is divided in three columns-STEP,
PROMPT, and PROCEDURE. The STEP column is the
numerical sequence the operator uses as he proceeds down
the form. The PROMPT column tells the operator what will
appear on the BUCS display at each particular step. The
PROCEDURE column tells the operator what action he
should take at each particular step or prompt.
FM 6-2
Table 5-4. Instructions for computing DA Form 5603-R
5-27
FM 6-2
Figure 5-19. Sample DA Form 5603-R
5-28
FM 6-2
Section V
LOCATION OF TRAVERSE ERRORS
A good survey plan executed by a well-trained party provides for numerous checks in both
computations and fieldwork. However, these checks do not always eliminate errors. On the contrary,
errors made both in fieldwork and in computations often are not discovered until the survey has
been completed. The FA surveyor must, therefore, be able to isolate these errors and determine
their causes. Often, a critical analysis of both the fieldwork and the computations of a survey in
error will save additional hours of repetitious labor and computation.
5-32. ANALYSIS OF TRAVERSE
FOR ERRORS
To rapidly analyze a survey, a well-trained chief of survey
party will maintain a sketch of the fieldwork, to state, of each
survey as it is being conducted. If a reliable map is available,
it will allow him to check errors that may occur in either the
fieldwork or the computations. If, upon completion of the
survey, an error is apparent, then the following assumptions
can be made. To isolate an error in a traverse, an assumption
must be made that only one error exists. If more than one error
exists, isolation of the error may not be possible. Under some
conditions, when there is more than one error in a traverse, an
apparent solution will exist; however, an investigation of the
error isolated may show that both fieldwork and computations
are correct for the station in question, When this condition
exists, no effort should be made to continue an analysis.
Instead, provisions should be made to perform the entire
traverse again. Table 5-5 lists the error indicators and the type
of error for a traverse closed on the starting point and closed
on a second known point. This table assumes that only one
error is made.
Table 5-5. Traverse error indicators
5-29
FM 6-2
5-33. ISOLATION OF
DISTANCE ERRORS
a. A distance error is indicated when the azimuth for the
traverse closes within tolerance but coordinate closure is in
error beyond the limits allowed for the prescribed accuracy.
b. Compare the known coordinates of the point on which
the survey was closed to the computed coordinates determined
by the survey. From this comparison, determine the error
in easting and the error in northing. Note the sign of each
error, and compute the azimuth from the known coordinates
of the closing station to the computed coordinates of the
closing station on DA Form 5590-R. The traverse leg
containing the distance error will have the same azimuth
(or back-azimuth) as the azimuth computed. (See Figure
5-20.) The distance computed will be the radial error. In
analyzing an error of this nature, some tolerance and
judgement must be used to determine the traverse leg in
error, This is because in both angular and distance
measurements, minor errors occur that are too small to affect
the overall accuracy but are large enough to make error
analysis difficult. Under some circumstances, several legs
with azimuths approximating the azimuths of the radial error
could contain the distance error. Check computations for
each suspected leg. If there is no error in computations,
then each suspected leg must be remeasured until the leg
containing the error is found.
Figure 5-20. Distance error
5-30
FM 6-2
5-34. ISOLATION OF
AZIMUTH ERRORS
a. Indication of Azimuth Error. An azimuth error is
indicated when the azimuth does not close within required
tolerance and coordinate closure is in error beyond the limits
allowed for the prescribed accuracy.
b. Isolation Procedure. Compare the computed azimuth
to the known azimuth of the closing point, and determine
the azimuth error. Compare the computed coordinates of
the closing station to the known coordinates, and determine
the error in casting and the error in northing. Compute the
distance (RE) and azimuth of the radial error by using DA
Form 5590-R, the known coordinates of the closing station,
and the computed coordinates of the closing station. Using
a scaled sketch of the traverse, construct a line perpendicular
to, and at the midpoint of, the plotted radial error line. Extend
this line in the appropriate direction through the area in
which the fieldwork was executed. (See Figure 5-21.) The
suspect station at which the angle error was made will be
on or very near the extended line.
c. Corrective Procedure. After the suspect station is
located, a check should be made of amputations at the
station to include the angular values in the field notes recorded
for that station. If there was no error in meaning of angles,
the angle for the station should be remeasured and compared
with the recorded angle measured as a part of the original
survey. This procedure will reveal the error, if one exists.
If the remeasured angle compares favorably with the recorded
angle, a multiple error exists in the survey and a solution
is not possible. When this situation occurs, the survey should
be rerun to determine the location of the errors.
Figure 5-21. Method of locating azimuth error in traverse
5-31
FM 6-2
d. Alternate Solution. The trial-and-error method is
another method that may be used to determine the location
of the angular error when a graphical plot of the survey is
not available or the perpendicular method does not isolate
one station. To determine suspect stations (stations where
the error may exist) by this method, first compute the distance
between the correct coordinates of the closing station and
the computed coordinates of the closing station. Second,
determine the amount the azimuth is in error by comparing
the closing azimuth with the correct grid azimuth at the
closing station. Third, substitute the distance error and the
azimuth error into the miI relation formula (w/r = m), and
determine the approximate distance (in kilometers) from the
closing station to the station in error. By this procedure,
one or more suspect stations may be determined. Then use
the trial-and-error method and systematic elimination to
locate the suspect station in error. Using the coordinates
of the suspect station and the known coordinates of the closing
station, compute the azimuth and distance between the two.
Using the coordinates of the suspect station and the computed
coordinate of the closing station, compute an additional
azimuth and distance between these two. Compare the results
with the azimuth and distance first determined. If the error
is at the suspect station, the azimuth should vary by the
amount of the azimuth error of closure and distances should
agree relatively closely. If the error is not at the suspect
station, the azimuth will disagree but not by an amount
equivalent to the azimuth closure error. (See Figure 5-22.)
5-35. ISOLATION OF
MULTIPLE ERRORS
Multiple errors are errors in both azimuth and distance or
more than one error in either azimuth or distance. When
there are multiple errors in a traverse, the indications will
be the same as for an azimuth error. It is possible that in
the procedure for azimuth error determination, definite
suspect stations will be located but an analysis of the
fieldwork and computations at these stations will not produce
the error. When this occurs, the entire traverse should be
performed again to locate the errors that were made.
Figure 5-22. Azimuth error
5-32
FM 6-2
Section VI
TRAVERSE ADJUSTMENT
Establishing a common grid throughout an entire corps or div arty sector is not as simple as it
may first appear. When a party is extending survey control over long distances by traverse, the
traverse may well be within the prescribed accuracy and still be considerably in error. This problem
is magnified when several traverse parties are used to extend control and try to tie their work
together. Seldom, if ever, will these parties coincide on their linkage. By adjusting the traverse,
throughout, however, some compensation will be made for those errors that have accumulated. A
traverse executed to a prescribed accuracy of fourth order must always be closed and adjusted.
An adjusted traverse is one in which the errors have been distributed systematically so that the
closing data determined by the traverse, coincide with the correct closing data. There is, of course,
no possible means of determining the true magnitude of the errors in angle and distance measurement
that occur throughout a traverse. Therefore, a traverse adjustment is based on the assumption that
the errors have accumulated gradually, and the corrections are made accordingly. Three adjustments
must be made when adjusting a traverse. These are azimuth, coordinates, and height, These
adjustments eliminate the effects of systematic errors on the assumption that they have been constant
and equal in their effect on each traverse leg. Traverse adjustment cannot compensate for blunders
such as dropped tape lengths or misread angles. Also, a traverse that does not meet the prescribed
standard of accuracy is not adjusted but is checked for error. If the error cannot be found, the
entire traverse must be performed again.
longer as the temperature increases and shorter as the
temperature decreases.
5-37. AZIMUTH ADJUSTMENT
5-36. SOURCES OF ERRORS
The errors for which traverse adjustment compensates are not
those errors commonly known as mistakes or blunders but are
errors that fall into one of the classes discussed below.
a. Instrumental Errors. These are errors that arise from
imperfections in, or faulty adjustment of, the instruments
with which the measurements are taken. For example, a
tape could be too long or the optical plumb might be out
of adjustment.
a. Determining Azimuth Correction. Since the computation of position depends partly on azimuth, the first step
in adjusting a traverse is to determine the azimuth error and
adjust the azimuth. The azimuth error is obtained by
determining the difference between the azimuth established
by traverse (computed) and the known azimuth at the closing
point. The azimuth correction is the azimuth error with the
proper sign affixed so that the computed azimuth with the
azimuth correction applied will equal the known azimuth.
b. Personnel Errors. These are errors that arise from the
limitations of the human senses of sight and touch. For
example, an error might be made in estimating the tension
applied to a steel tape or in plumbing a plumb bob over a
point.
c. Natural Errors. Natural errors arise from variation in
the phenomena of nature, such as temperature, humidity,
wind, gravity, and refraction. For example, the length of a
tape varies directly with the temperature. The tape becomes
5-33
FM 5-2
b. Application of Azimuth Correction. Since traverse
adjustment is based on the assumption that errors present
have accumulated gradually and systematically throughout
the traverse, the azimuth correction is applied accordingly.
The correction is distributed equally among the angles of
the traverse with any remainder distributed to the larger
angles. For example, assume that the traverse for which
the azimuth correction was determined consisted of three
traverse legs and four angles. The azimuth correction is
divided by the total number of angles. In this case, +0.070
mil + 4 = 0.017 mil per angle with a remainder of 0.002
roil. Each of the four angles will be adjusted by 0.017 roil,
and the two largest angles will be adjusted by an additional
0.001 mil each to compensate for the remaining 0.002 roil.
5-38. COORDINATE ADJUSTMENT
a. Determining Easting and Northing Corrections. The
casting and northing corrections for the traverse are
determined by algebraically subtracting the coordinates of
the closing station (as recomputed with the adjusted azimuth)
from the known coordinates of the closing station.
b. Application of Easting and Northing Corrections. The
corrections determined in a above are for an entire traverse.
It is assumed that these corrections are based on errors
proportionate y accumulated throughout the traverse.
Therefore, the corrections must be distributed proportionately
throughout the traverse. The amount of casting or northing
correction to be applied to the coordinates of each station
is computed by multiplying the total correction (casting or
northing) by the total length of all the traverse legs up to
that station and dividing the result by the total length of all
of the legs in the traverse For example, using the total
casting and northing corrections previously determined,
assume the total length of the traverse is 22,216.89 meters
and the total length of the traverse legs up to TS 4 is 3,846.35
meters.
c. Action After Adjustment. After the angles have been
adjusted, the adjusted azimuth of each leg of the traverse
should be recomputed by using the starting azimuth and
adjusted angles at each traverse station. These computations
should be performed on clean copies of DA Form 5591-R,
not on the forms used for the original computations. The
adjusted azimuth should be computed throughout the entire
traverse and checked against the correct azimuth to the closing
azimuth mark before adjusting the coordinates After the
azimuth of each traverse leg has been adjusted, the coordinates
of the stations in the traverse must be adjusted. The first
step in adjusting the coordinates is to recompute the
coordinates of all stations in the traverse, using the adjusted
azimuths. It is now assumed that all azimuth error has been
eliminated. Any remaining error is assumed to be a distance
error.
5-39. HEIGHT ADJUSTMENT
a. Height adjustment is based on the assumption that the
error of closure of height is accumulated throughout the
traverse in equal amounts at each traverse station and not
proportionately to the length of the traverse legs. Errors
caused by this assumption have no effect for FA purposes.
5-34
FM 6-2
b. The height correction is the error in height with the sign
reversed. It is determined by comparing the height of the
closing point established by the traverse with the known
height of the closing point and applying a sign (±) that will
cause the established height, with the algebraic correction
applied, to equal the known height. For example, if the
known height is 478.3 meters and the computed height
(established by traverse) is 477.5 meters, the height correction
would be 0.8 meter (478.3 - 477. S). For the height determined
by traverse to equal the correct height, 0.8 meter would
have to be added to the height of the closing station
determined by traverse.
c. The height correction is distributed equally among the
stations of the traverse with any remainder distributed to
those stations computed from the longest legsi. Assume that
the traverse for which the height correction was determined
consists of four stations. To distribute the height correction
throughout the traverse, divide the height correction by the
total number of stations in the traverse excluding the starting
station (a known height). In this case, 0.8 meter +3 stations
= 0.2 meter with a remainder of 0.2 meter to be divided
and applied equally to those stations computed from the
longest legs. The adjustment would be as shown in the
example below. The adjustment is an accumulation of the
correction, since the correction is applied to the differences
in height between the stations and not directly to the station
heights. The height adjustment can be made on the same
form and at the same time that coordinate adjustments are
being made.
5-40. DISCRETION ADJUSTMENT
Although traverse adjustment is a systematic operation, there
will be times in the field when surveyors may rely on
judgment alone. In these case-s, the error maybe distributed
arbitrarily in accordance with the surveyor’s estimation of
the field conditions. It is reasonable to assume that if certain
legs of the traverse are over rough terrain, the error in taping
these legs will be relatively large compared to taping over
ideal terrain and the correction should be correspondingly
greater. If lines of sight are steep and visibility is poor,
larger angular errors would be expected than when observing
conditions are relatively favorable. The artillery surveyor
should not resort to this method of adjustment unless he is
experienced and has a keen knowledge of where errors are
most likely to occur and of their effect on the overall survey.
In any event, the field notebook should contain a detailed
account of any unfavorable survey conditions so that it may
be used to substantiate any arbitrary adjustments.
5-35
FM 6-2
CHAPTER 6
TRIANGULATION
Triangulation is a method of conventional survey used when the traverse
method is impractical or impossible. This method is ideally suited to rough
The triangulation method employs oblique
or mountainous terrain.
triangular figures and enables the surveyor to cross obstacles and long
distances. This method is time-consuming and requires careful planning
and extensive reconnaissance.
Section I
METHODS AND OPERATIONS
The triangulation method of survey uses triangular figures to determine survey data. If the values of
certain elements of a triangle are known, the values of other elements of the triangle can be computed.
6-1. SURVEY METHODS USING
TRIANGLES
a. In FA surveys, the term triangulation is restricted to
operations that involve the measurement of all angles within
a triangle, (See Figure 6-l.) Other methods of survey,
however, use the triangular figure, but the procedures used
Figure 6-1. Triangulation
in the fieldwork and in the computations differ somewhat
from the methods used in triangulation. Two of these
methods used in FA survey are intersection and resection.
(1) In the intersection method, two angles are measured.
If the length and azimuth of one side and two angles are
known, the intersection can be computed. (See Figure 6-2.)
Figure 6-2. Intersection
6-1
FM 6-2
(2) In resection, the coordinates of an unknown point
are obtained by determining the horizontal angles at the
unknown point between three unoccupied points of known
coordinates. (See Figure 6-3.)
b. Survey methods using the triangular figure may be used
at all levels of FA survey to establish the locations of survey
control points. Generally, it is better to use some method
of survey that employs these procedures if the distance or
terrain involved makes traverse difficult or impossible.
Figure 6-3. Three-point resection
c. Triangulation involves single triangles (Figure 6-1) and
chains or schemes of triangles (Figure 6-4). Whether a
particular triangle is a single triangle or part of a scheme
of triangles, the angles in the triangle are determined in the
same manner, and the unknown elements of the triangle are
computed in the same manner. In a single triangle, the base
(known side) is measured with electronic distance-measuring
devices or a 30-meter steel tape, or it is computed from
known coordinates of the required accuracy. In a chain of
triangles, the base of the first triangle is determined in the
same manner as a single triangle. The base for the second
triangle is the side of the first triangle that is common to
both triangles. This side is computed, which establishes a
base distance for computation of the second triangle. The
same procedure is used to determine the base for each triangle
in a triangulation scheme.
6-2. TRIANGULATION PARTIES
Figure 6-4. Chain of triangles
a. Triangulation operations are not confined to one area at
any one time.
Several operations are involved in
triangulation. The personnel involved in each phase are
usually separated from the personnel performing other phases
of the survey. Since different lengths of time are required
for the various operations, no standard division of duties
can be made. There are general operations that must be
performed in triangulation, and each of the survey personnel
is assigned to one or more of these functions. The general
operations are as follows:
Ž Reconnaissance and planning.
Ž Determination of angles.
Ž Base measurement.
Ž Computation.
b. The recon party normally consists of the survey officer
and/or the chief surveyor and such other personnel as deemed
necessary. The recon party selects and marks each station
to be used in the triangulation scheme. It also may erect
a target over each station. If considerable clearing of trees
and underbrush is required near the station, clearing may
be performed by either the recon party or the angle-measuring
personnel. Additional personnel may be required in the party
that does the clearing. (Usually, the time and personnel
available to perform artillery surveys preclude extensive
clearing of trees and underbrush.)
c. The angle-measuring party consists of the instrument operator,
the recorder, and (when necessary) personnel for clearing.
6-2
FM 6-2
d. When the base is measured with the SEDME-MR a team
of two men is required. This team consists of one instrument
operator-recorder and one man to set up the reflector prism
at the end of the base. If taping teams are used, the base
is double taped to the specified comparative accuracy. If
only one taping team is available, it must make at least two
independent measurements of the base to the specified
comparative accuracy. A tension handle with a 25-pound
pull should be used, and horizontal alignment must be
maintained to ensure the required accuracy of a taped base
measurement. If SEDME-MR devices are used to measure
the base, the base will be measured three times and the
mean reading used to compute the base. After completing
all required measurements, these personnel may be used as
directed by the chief of party or the survey and recon officer.
e. The computing party consists of two computers (one has
a dual role of computer-recorder). The computers make
independent computations and compare their results. They
make their computations at any convenient location specified
by the party chief or the survey officer. Data from the
various points in the survey are reported to the computer
by some prearranged method (for example, by
radiotelephone).
6-3. TRIANGULATION FIELD NOTES
a. As the bases are measured, each tapeman of the two
taping teams records all the base measurements in the taping
notebook. As soon as practical, these recorded distance-s
are transferred to the field notes kept by the recorder. When
the base length is measured with the SEDME-MR, the
recorder at the end of the base at which the SEDME is
located enters the distance in the field notebook.
b. The field notes kept by the recorder in an angIe-measuring
party are discussed in Chapter 4. Figures 4-7 through 4-9
are examples of notes kept by a recorder for 1 :1,000 (T16
theodolite) and 1:3,000 (T2 theodolite) triangulation.
6-4. STANDARDS AND SPECIFICATIONS
In triangulation, fieldwork and computations adhere to certain
standards and specifications to produce surveys of the desired
accuracy. These standards and specifications are described
in Appendix B.
Section II
TRIANGULATION COMPUTATION
A triangle is defined as a closed the-sided geometric figure containing three interior angles the sum
of which is 3,203 mils. Each triangle is solved separately whether it is a single triangle or a triangle
in a scheme. The only type of triangulation problem (excluding intersection and resection) involved
in artillery surveys is the solution of a triangle in which the values of all three angles and the length
and azimuth of one side are known. This type of problem is solved by using DA Form 5592-R
(Computation of Plane Triangle Coordinates and Height From One Side, Three Angles, and Vertical
Angles (BUCS)). (A reproducible copy of this form is included at the back of this book.)
a. Select two other points, B and C, intervisible to each
other and Point A. The coordinates and height of at least
one of these two points must be known.
6-5. SURVEY APPLICATION OF
BASIC TRIANGLE
To determine the coordinates and height of a point from
another point of known coordinates and height requires three
items of information-vertical angle, azimuth, and distance.
To associate the basic triangle in Figure 6-5 with these
objectives, assume that Point A of this triangle is a point
at which the coordinates and height are to be determined
by triangulation. To do this, take the steps discussed below.
b. Measure the horizontal interior angles and vertical angles
at Points A, B, and C with an instrument. With one more
item, a known side (the base), the triangle can be solved.
The specifications for angle measurement for fourth- and
fifth-order accuracies are shown in Appendix B.
c. The length of the base can be obtained in either of two
ways-by direct measurement or by computation (see (1)
below). As mentioned earlier, the coordinates and height
of Point B or C must be known. The specifications for
baseline measurement for fourth- and fifth-order accuracies
are shown in Appendix B.
6-3
FM 6-2
(1) If the coordinates and height of both B and C are
known, the azimuth and length of the base (the line joining B
and C) can be computed on DA Form 5590-R. These known
coordinates and heights must be of an equal or higher accuracy
than that of the survey being performed. (If a fourth-older
survey is being conducted, the coordinates used to compute the
azimuth and length of the base should be of third-order accuracy
or higher but must be at least fourth-order accuracy.)
(2) If the coordinates of only one of the points are known,
the base length must be taped or measured electronically.
The azimuth must be obtained by astronomic observation,
by gyroscopic means, or by sighting on a point of known
azimuth (azimuth mark).
Figure 6-5. Distance angles of a single triangle
d. When the three horizontal interior angles, vertical angles,
azimuth of the base (thus, the azimuths of all three sides), and
length of the base have been determined, the triangle can be
solved to determine coordinates and height of A. The decision
as to which side to compute will be based on distance angles.
c. The difference between the sines of angles near 0 mils
or 3,200 mils is quite large for very small differences between
angles. Because of this, a small error in the value of an
angle near O mils or 3,200 mils will cause a relatively large
error in the sine of the angle and a corresponding error in
the computed length of the side opposite the angle.
Therefore, for beat results, distance angles must be at least
400 mils and preferably 533 mils For this reason, in the
case of a single triangle, the side opposite the stronger angle
is the side computed.
6-6. DISTANCE ANGLES OF A SINGLE
TRIANGLE
a. Only strong figures should be used in triangulation to minimize
the effects of small measurement errors. The ideal figure is
an equilateral triangle. However, field conditions generally
make the use of the ideal figures impractical, and often figures
must be selected that only approximate the ideal.
b. Computing the length of a side in a triangle involves two
of the three angles in the triangle. The angles involved in the
computation of the length of a side are called distance angles.
Distance angles are defined as those angles in a triangle opposite
the known side (base) and the required side (side common to
an adjacent triangle). Since in a single triangle there is no
specific required side, the distance angles in a single triangle
are the angles opposite the known side and the stronger (closest
to 1,600 mils) of the two remaining angles. (See Figure 6-5.)
6-4
d. Vertical angles at each end of the side of a triangle should
be measured reciprocally to the height of instrument. Often,
because of distances involved, the instrument operator must
measure the vertical angle to a target erected and plumbed
over the forward station. When the triangulation stations
are greater than 1,000 meters, the vertical angle is measured
reciprocally. In any triangulation scheme, the coordinates
and height of at least one station must be known. This
station is used as the starting point to obtain the height of
the next station. The height control is extended along the
forward line of each triangle in the scheme. In Figure 6-6,
use the height of Point Dave as a starting point, since the
height of Point John must be computed along the forward
line (Dave-John). Using the height of Point John, compute
the height of Point Bill and the height of Point Mike. If
side Bill-Mike had been the forward line, then the
computation would have been from Point Bill to Point Mike.
FM 6-2
Figure 6-6. Route of trigonometric
height computations
Section Ill
TRIANGULATION SCHEMES
A chain (scheme) of triangles is a series of single triangles connected by common sides. (See Figure
6-4.) In a chain of triangles, only the length of the first, or original, base and the length of each check
base are measured. The lengths of all other sides are computed.
6-7. DESCRIPTION, SOLUTION, AND
CHECKS OF A CHAIN OF TRIANGLES
a. In Figure 6-7, side John-Bill is common to triangles
John-Bill-Joe and Mike-Bill-John. Each of these triangles
may be solved individually if one side and the interior angles
are known. In Figure 6-7, assume there is a requirement
to locate an additional point, Mike, outside the single triangle
John-Bill-Joe. While the interior and vertical angles at John
and Bill are being measured, the angles for the new triangle
would also be measured. Then the horizontal and vertical
angles at Point Mike would be determined. Since side
Joe-Bill is a known side, all the information needed to
compute both triangles would then be available. Side
John-Bill would be the required side (side John-Bill is
common to both triangles), and the angle at Point Joe would
be its distance angle, regardless of its value. A distance
angle is an angle in a triangle opposite the known side and
the angle opposite the required side (side common to an
adjacent triangle). The required side is also known as the
forward line or forward base, because it will become the
base for the next triangle in the scheme. In a chain of
triangles, the last triangle in the scheme is computed as a
single triangle, and its distance angles are determined as
discussed in paragraph 6-6b. For example, in Figure 6-7,
the distance angles in triangle John-Bill-Joe are at points
John (angle opposite known side Joe-Bill) and Joe (angle
opposite the required side). For triangle Mike-Bill-John,
the distance angles are at Point Mike (angle opposite known
side John-Bill, which has been solved in triangle
John-Bill-Joe) and Point Bill (the stronger of angles at John
and Bill).
6-5
FM 6-2
Figure 6-7. Relationship of a single triangle to
a chain of triangles
b. The size of the distance angles in a triangle is used as
the measure of relative strength of the figure. The strength
factor of a triangle is determined by use of a strength of
figure factor table. (See Table 6-l.) The distance angles of
the triangle serve as arguments for entering the table, the
smaller distance angle dictates the column; the larger distance
angle, the row. The smaller the factor, the greater the relative
strength of the triangle.
c. When the sum of the strength factors of a chain of triangles
exceeds 200 or at every fifth triangle, a check base (the
required side) and azimuth must be determined. If the
difference between the computed length and azimuth and
the measured length and azimuth is within prescribed
tolerances, the scheme may be continued with the measured
data. For fifth-order surveys, the computed length of the
check base must agree with the measured length within
1:1,000 (comparative accuracy), and the computed azimuth
must agree with the astronomic (astro) or gyroscopic (gyro)
azimuth within 0.1 times the number of main scheme angles
used to carry the azimuth to the check base. For fourth-order
surveys, the check comparisons are 1:3,000 (comparative
accuracy) for the base and 0.04 x N, where N is the number
of main scheme angles used to carry the azimuth to the
check base.
Table 6-1. Table for determining strength of figure factors (mils)
6-6
FM 6-2
d. A chain of triangles does not provide enough internal
checks for an estimation of the accuracy of the work
performed. As a check, the length of the last computed
side of the final triangle is measured and the computed and
measured lengths are compared. The results of this
comparison must produce a comparative accuracy as shown
in c above. The azimuth of the last computed side must
be determined by astro or gyro observation as soon as
possible. Error in azimuth is determined by comparing the
astro or gyro azimuth with the azimuth computed through
the scheme as described in c above. If the scheme closes
on a known point, an accuracy ratio must be determined.
The total length used for computing the accuracy ratio is
the sum of the lengths of the sides of the triangles used to
compute coordinates in the scheme from starting station to
closing station. The azimuth is verified by turning a closing
angle to an azimuth mark. The sum of the closing angle
and the azimuth of the base must agree with the known
azimuth within the accuracies stated in c above. (See Figures
6-8 and 6-9.)
Figure 6-8. Determining distance for
accuracy ratio
Figure 6-9. Determining number of angles for
azimuth closure
6-7
FM 6-2
6-8. TRIANGLE CLOSURE
When interior angles of a triangle are measured in the field,
the sum of the angles may vary from 3,200 mils by a small
amount. The term used to describe this variance is triangle
closure. If the variance is within tolerance (Appendix B),
the angles are adjusted to equal 3,200. The BUCS will
automatically do this by distributing the closure variance
equally among the three angles. The BUCS will display
the closure. (See Figures 6-10,6-11, and 6-12 for triangulation
computations.)
the succeeding unknown stations will be labeled in order of
computation. In Figure 6-10, Station Ben is number one
because it is the point where the known and required side
meet. Station Sue is labeled “#2,” since it is the first unknown
point. The next unknown station (Bill) is labeled “#3.”
(2) Steps 1 through 8 of the DATA RECORD section
are used to record the data for the starting known point (B
or C), to include the azimuth and distance of the starting
base. If there is more than one triangle to be computed,
data from subsequent triangles are also recorded in this
section. (See Figure 6-11.)
6-9. DA FORM 5592-R
a. DA Form 5592-R is used for computing triangulation
schemes. The front of the form is designed for the solution
of one triangle and for entering the field data for a second
triangle.
b. DA Form 5592-R has five major sections used for
computations. These sections are described in (1) through
(5) below in the sequence in which they should be computed.
(1) The SKETCH: block is provided for the user to draw
a sketch of the triangulation scheme or the single triangle.
The sketch should be properly labeled with the station angles,
station names and numbers, the starting base, and all the
required sides for determining data.
(a) Label triangle 1 as follows: Station A is always
located at the first unknown point (station opposite the starting
base), and then stations B and C are labeled in a clockwise
manner. In Figure 6-10, station Sue is labeled “A”; station
Rob, "B;" and station Ben, “C.” For succeeding triangles, the
station that is opposite the side common to both triangles (see
paragraph 6-7a) is labeled "A," and so forth.
(b) Before starting computations, the stations must be
numbered. Station 1 is located at one end of the starting base
(BC), This is the station where the known side and required
side meet, Station 2 is the first unknown point (Station A),
6-8
(3) Steps 9 through 12 of the DATA RECORD section
are provided for the field data as determined by the
angle-measuring party (horizontal and vertical angles).
(4) Steps 1 through 13 of the DATA RECORD section
on the reverse of the form are used when the triangulation
scheme is closed on a known point. The known data of
the point must be provided so the BUCS can compute the
azimuth error, height error, radial error and the accuracy
ratio for the triangulation scheme. Refer to paragraph 6-7d.
(5) Steps 1 through 6 of the DATA RECORD section
on the bottom reverse of the form are used when the
triangulation scheme requires a check base, For guidance
on when to compute a check base, refer to paragraphs 6-7c
and d.
FM 6-2
Figure 6-10. DA Form 5592-R (front)
6-9
FM 6-2
Figure 6-11. DA Form 5592-R (front) (continued)
6-10
FM 6-2
Figure 6-12. DA Form 5592-R (reverse)
6-11
FM 6-2
Table 6-2. Instructions for computing DA Form 5592-R
6-12
FM 6-2
Table 6-2. Instructions for computing DA Form 5592-R (continued)
Table 6-3. Closure on known point computation, reverse of DA Form 5592-R
6-13
FM 6-2
Table 6-3. Closure on known point computation, reverse of DA Form 5692-R (continued)
Table 6-4. Check base computation, reverse of DA Form 5592-R
6-14
FM 6-2
Section IV
INTERSECTION
Intersection is a method of survey used to locate an unknown point by determining azimuths from two
or more known points. This method of survey is used as a means of establishing control to desired
positions and of checking the locations of points established by other survey methods. A point
established by the intersection method should be observed from at least two known stations of equal
or higher order of survey than the survey being conducted. One of the points is designated as 01. The
height of 01 must also be known. The location and height of the unknown are computed from 01.
6-10. LIMITATIONS
Figure 6-13. Intervisible points
Limitations for the apex angle are the same as the limitations
for distance angles discussed in paragraph 6-6c. (The
exception to this is when intersection is used in target area
survey. In this case, the apex angle must be at least 150
mils and preferably 300 mils.)
6-11. POINT VISIBILITY
The known points can be either intervisible or nonintervisible.
a. If the points are intervisible (Figure 6-13), measure a
horizontal angle from each point to the unknown point, using
the other point as the rear station. Measure a vertical angle
from 01 to the unknown point. Compute the azimuth between
the two points by using DA Form 5590-R. Then separately
add each angle to the azimuth or back-azimuth to determine
the azimuths from 01 and 02 to the unknown point.
b. Determine if the apex angle meets the requirements (see
paragraph 6-10) by doing the procedure below.
(1) Determine the back-azimuths from the unknown point
back to the known points by adding or subtracting 3,200 mils
6-15
FM 6-2
(2) Imagine yourself standing at the unknown point
looking back at the known points. (See Figure 6-13.) Point
02 is located to the left side and Point 01 to the right. Subtract
the azimuths from left to right.
c. If the points are nonintervisible (Figure 6-14), do the
procedure below. (See the example below.)
(1) Measure a horizontal angle from both points to the
unknown point by using a point with a known azimuth as
a rear station. Each angle is then added separately to the
known azimuth to determine the azimuths from 01 and 02
to the unknown point.
(2) Determine if the apex angle meets the requirements
as described in paragraph 6-1 lb.
6-12. INTERSECTION COMPUTATIONS
Intersection computations are done on DA Form 5604-R
(Computation of Coordinate and Height by Intersection
(BUCS)). (See Figure 6-15.) (A reproducible copy of this
form is at the back of this book.) (Table 6-5 gives the
instructions for computing DA Form 5604-R.)
Figure 6-14. Nonintervisible points
6-16
FM 6-2
Figure 6-15. DA Form 5604-R
6-17
FM 6-2
Table 6-5. Instructions for computing DA Form 5604-R
6-18
FM 6-2
Table 6-5. Instruction for computing DA Form 5604-R (continued)
6-13. INTERSECTION ACCURACY
To determine the accuracy of an intersection, do the procedure
below.
a. Compute another intersection to the unknown (unk) point
by using a different Point 01, Point 02, or Points 01 and
02.
b. Compute a DA Form 5590-R from the points designated
as 01 to the unknown point.
c. Then compute a DA Form 5590-R from the computed
coordinates of the first intersection to the computed
coordinates of the second intersection. (This will be the radial
error.)
d. Divide the radial error into the shorter of the two distances
(dis), 01A to the unknown point or 01B to the unknown
point. This will be the accuracy ratio of the intersection.
The accuracy ratio must agree within the prescribed accuracy
limits for the type of survey being performed (1:1,000 for
fifth order, 1:3,000 for fourth order).
e. Once the accuracy ratio has been computed and meets
specifications described in d above, determine the mean
coordinates and elevation for the unknown point. (See Figure
6-15, REMARKS: block.)
6-19
FM 6-2
Section V
THREE-POINT RESECTION
Three-point resection is a method of survey used to obtain control for an unknown point on the basis
of three inaccessible known points. However, before the fieldwork is begun, several factors must be
considered. In Figure 6-16, Stations A, B, and C are the known points and Station P is the occupied
station for which coordinate are to be determined. All points must be selected so that Angles P1, P2,
C, and B (Figure 6-16) are at least 400 mils The preferred value for the angles is 533 rnils. Also, if
the sum of the Angles P1, P2, and Al is between 2,845 mils and 3,555 mils no valid solution is possible.
This simply means that Station P lies on or near a circle passing through Stations A, B, and C. To
eliminate the possibility of this occurring, a map reconnaissance must be made. The fieldwork consists
of measuring horizontal Angles P1 and P2 and the vertical angle to the center station. Resection field
notes are recorded in the field notebook in the same basic format as triangulation field notes except
that the height of target (known or estimated) and the height of instrument (measured to the nearest
0.1 meter) are recorded in the remarks section. A three-point resection may be considered a closed
survey if a fourth known point is used to compute a second resection, the solutions are compared, and
the accuracy ratio meets the specified position closure requirement. The points used for three-point
resection should be fourth-order or better. For an example of the field notes of a three-point resection,
see Figure 4-11 in Chapter 4.
Figure 6-16. Three-point resection
Ž Computer’s name.
Ž Checker’s name.
Ž Area in which survey was performed.
Ž Notebook reference.
Ž Date the computations were performed.
Ž Identification of the sheet number.
b. The next part of the form provides notes for specific
operations of the program and other notes necessary for
completion of this form.
6-14. DA FORM 5593-R
a. DA Form 5593-R (Computation of Coordinates and
Height by Three-Point Resection (BUCS)) is shown in Figure
6-17. (A reproducible copy of this form is included at the
back of this book.) The top of the form is for recording
administrative data, These data include the following:
6-20
c. The form is divided into two major sections. The section
on the left provides instructions for the computer. The right
section (DATA RECORD) is for recording data-both field
and computed. Two resections can be computed on each
form. The left section is divided into three columns—STEP,
PROMPT, and PROCEDURE, The STEP column is the
numerical sequence the operator uses as he proceeds down
the form The PROMPT column tells the operator what
will appear on the BUCS display at each particular step.
The PROCEDURE column tells the computer the action he
will take at each particular step or prompt.
d. Entries required are the coordinates of Points A, B, and
C, the horizontal and vertical angles measured at Point P;
and the height of Point A. The points used for three-point
resection should be of fourth-order or higher accuracy.
FM 6-2
Figure 6-17. DA Form 5593-R
6-21
FM 6-2
Table 6-6. Instructions for computing DA Form 5593-R
6-22
FM 6-2
Table 6-6. Instructions for computing DA Form 5593-R (continued)
6-15. CHECKS AND CLOSURE
Figure 6-18. Three-point resection, fourth
known station
When possible, the checks below are made to verify data obtained
by three-point resection.
a. A horizontal angle to a fourth known station is measured.
This will give another three-point resection from which the
coordinates of Point PI (a second location of P) may be
determined. (See Figure 6-18.) An accuracy ratio is
computed by the following formula:
(1) Compute DA Form 5590-R by using the coordinates
of the established point to the center station of the first
resection (P-CENTER). (See Figure 6-17, REMARKS:
block.)
(2) Then compute DA Form 5590-R from the computed
coordinates of the second resection to the center station
(P1-CENTER 1).
(3) Compute DA Form 5590-R from the computed
coordinates of the first resection to the computed coordinates
of the second resection (T-P1). The distance will be the
radial error.
(4) Divide the radial error into the shorter of the two
distances—P-CENTER or P1-CENTER 1. The result is the
accuracy ratio of the intersection. The accuracy ratio must
agree within the prescribed accuracy limits for the type of
survey being performed (1:1,000 for fifth order, 1:3,000 for
fourth order).
b. An astronomic azimuth or gyroscopic azimuth is determined to check the azimuth.
c. If a fourth point (a above) is not known, then Point P
must be verified by some other method of survey before it
can be used to extend control.
6-23
6-16. LAW OF SINES
As shown in Figure 6-19, the law of sines is a straight
proportion-type formula which states that the sine of the
angle at A is to its opposite side as the sine of the angle
at B is to its opposite side or the sine of the angle at C is
to its opposite side. If the value of each of the interior angles
of the triangle were known and the length of side a were
known, the law of sines would be transposed as shown in
b and c below.
a. Ensure the BUCS is operating in degrees. (Type
DEGREES, and press the END LINE key.)
b. To determine the length of side b, use the following
formula:
The formula when using the BUCS is as follows:
side b = side a * SIN(Angle B * .05625)/ SIN(Angle A *
.05625) END LINE
c. To determine the length of side c, use the following
formula:
The formula when using the BUCS is as follows:
6-24
side c = side a * SIN(Angle C * .05625)/ SIN(Angle A *
.05625) END LINE.
Figure 6-19. Law of sines as it applies to
a basic triangle
FM 6-2
CHAPTER 7
ASTRONOMY FOR FIELD ARTILLERY
The FA surveyor can determine an accurate azimuth rapidly and easily
by observation of the sun or stars. These astro observations provide true
azimuths, which are converted to grid azimuths by applying grid
convergence.
Section I
BASIC ASTRONOMY
The FA surveyor uses practical astronomy to perform his mission. Practical astronomy is used to
determine time, position, and azimuth. The FA surveyor observes celestial bodies only to determine
azimuth. High-order survey organizations determine position by astro observation. The key to
gaining a working knowledge of practical astronomy is learning its terms. The following paragraphs
and the Glossary define the common astronomic terms.
7-1. EARTH
Figure 7-1. Rotation of the earth
a. The earth has the shape of a flattened sphere. The line
connecting the flattened ends of the earth is the axis of the
earth. The points at either end of this axis are the North
and South Poles.
b. The earth has two important motions to the
surveyor-rotation and revolution.
(1) Rotation. Rotation refers to the turning of the earth
on its axis. The earth rotates from west to east, making one
complete rotation in a period of about 24 hours. (See Figure
7-l.)
(2) Revolution. The earth revolves about the sun on a
600-million-mile orbit at a speed of about 18.5 miles per
second. The average distance to the sun is 93 million miles.
The earth’s orbit is an ellipse, having the sun at one focus.
The axis of the earth is tilted 23.5° from the perpendicular
to the plane of its orbit around the sun. This tilting gives
us our seasons. On the first day of spring and of fall, about
the same amount of sunlight is received in both the Northern
and Southern Hemispheres. During the winter in the Northern
Hemisphere, no sunlight reaches the north arctic regions,
which causes wintry weather to extend south to the lower
latitudes. The reverse is true during the summer in the
Northern Hemisphere. (See Figure 7-2.)
7-1
FM 6-2
Figure 7-2. Earth’s orbit about the sun
c. Since adapting a rectangular coordinate system to a sphere
is impractical, a system using angular measurements was
adopted.
(1) Latitude. Planes were passed through the earth, all
parallel to each other and perpendicular to the rotating axis
of the earth. The lines that these planes inscribe on the earth’s
surface are called parallels of latitude. The parallel of latitude
halfway between the poles is called the equator. This parallel
is given a value of 0° and is used as the basis for measuring
latitude. Latitude is measured in units of degrees, minutes,
and seconds north or south of the equator (34°48’12” N or
30°12’16” S) Up to 90°.
(2) Longitude. Other planes were passed through the earth
so they intersect at both poles. The lines these planes inscribe
on the surface of the sphere are called meridians of longitude.
A baseline for measurement was established with the meridian
that passed through Greenwich, England, and was given a
value of 0°. Longitude is measured in units of degrees,
minutes, and seconds east (E) and west (W) of the Greenwich
meridian (for example, 90°24’18” W or 40°12’43” E) up to
180°.
7-2. CELESTIAL SPHERE
a. In practical astronomy, the sun and stars are considered
fixed onto a sphere of infinite radius. At the center of this
sphere is the eye of an observer. The observer is resumed
7-2
to be located at the center of the earth. This imaginary
sphere of infinite radius is called the celestial sphere. The
celestial sphere allows us to solve all problems of astro
observations by using spherical trigonometry.
b. The celestial sphere appears to rotate about an axis.
However, this apparent rotation is due to rotation of the
earth about its axis from west to east in a counterclockwise
movement and is opposite in direction to that in which the
stars appear to move. In practical astronomy, the earth is
regarded as stationary and the celestial sphere revolves about
the earth from east to west.
7-3. SPHERICAL COORDINATES
a. Reference points, such as the poles, the equator, meridians
of longitude, and parallels of latitude, are used to determine
the location of points on the surface of the earth. Spherical
coordinates are used to determine the location of points on
the celestial sphere. There are two systems of spherical
coordinate—the horizon system and the equator system.
The artillery surveyor uses the equator system.
b. Since the earth is assumed to be the center of the celestial
sphere, the North and South Poles of the earth can be extended
to the sphere where they become the celestial North and
South Poles. Likewise, the plane of the earth’s equator,
extended to the celestial sphere, becomes the celestial equator,
(See Figure 7-3.)
FM 6-2
c. The observer's position on earth is located by latitude
Figure 7-3. Celestial sphere
established on the sphere. The arc distance between the zenith
of the observer and the celestial equator is the same as the
arc distance, in latitude, between his position on the surface
of the earth and the earth’s equator. The longitude of the
observer is the arc on the equator between the Greenwich
meridian (0° prime meridian) and the observer’s meridian.
On the celestial sphere, the longitude is the are on the celestial
equator between the planes of the Greenwich meridian and
the meridian of the observer extended to intersect the celestial
sphere. (It is also the angle at the pole between the planes
of the two meridians.) When latitude and longitude are used
in this manner and projected to the celestial sphere, the
position of the observer’s instrument is fixed at a point on
the celestial sphere known as the zenith. (See Figure 7-4.)
d. The FA surveyor uses right ascension and declination to
identify the location of a star on the celestial sphere. In the
equator system of spherical coordinates, there must be points
of origin. The points of zero reference in the equator system
are the vernal equinox (VE) and the celestial equator.
Figure 7-4. Celestial sphere—geographic coordinate relationship
7-3
FM 6-2
(1) During each year, the sun traces a path, called the
ecliptic, on the celestial sphere. This path is caused by the
tilt of the minor axis of the earth with respect to the plane
of its orbit. (See Figure 7-5.) This path of the sun moves
from the Southern Hemisphere of the celestial sphere to the
Northern Hemisphere and back. The point where the sun
crosses the celestial equator in its movement from south to
north along the ecliptic is known as the vernal equinox, the
first day of spring. The vernal equinox is the first point of
reference in the equator system of spherical coordinates. It
also is used in the same manner that the prime meridian of
Greenwich is used as a point of reference.
Figure 7-5. Ecliptic, equinoxes, and solstices
(2) The celestial equator, the plane of the earth equator
extended to the celestial sphere, is the second point of
reference. It divides the celestial globe into celestial Northern
and Southern Hemispheres. The declination (see Glossary)
of the celestial equator is 0° or 0 mils (e(2) below), just as
the earth’s equator is 0° or 0 mils latitude.
e. Since the stars appear to rotate about the earth, it is
necessary to have a fixed point that can be readily identified
and whose location in time relative to the Greenwich meridian
can be computed for any given moment, (See the discussion
of sidereal time in paragraph 7-7.) The fixed point is the
vernal equinox, the point where thes un crosses the celestial
equator from south to north on or about March 21, the first
day of spring. Once the position of the vernal equinox is
known, it is possible to identify the relative location of any
prominent star by knowing how far it is from the vernal
equinox and whether it is north or south of the celestial
equator, the second fixed reference. (See Figure 7-6.)
(1) The spherical coordinate right ascension (RA) is the
arc distance eastward along the celestial equator from the
vernal equinox to the hour circle (see Glossary) of the star.
It may be measured in degrees (°), minutes (’), and seconds
(“) of arc or in hours (h), minutes (m), and seconds (s) of
time. The latter is the normal means of expression and can
be from Oh to 24h east of the vernal equinox.
(2) Declination, the second spherical coordinate, is the
star’s angular distance north or south of the celestial equator
measured on the hour circle of the body. North declination
is plus (+), and south declination is minus (-). Declination
can be from 0 mils to 1,600 mils north or south of the
celestial equator. (See Figure 7-6.)
f. The observer’s horizon is the plane tangent to the earth
at the observer’s position and perpendicular to his plumb
line extended to the celestial sphere. The observer’s horizon
is used as a reference for determining the altitude of a celestial
body. It is discussed in detail in paragraph 7-4.
7-4
Figure 7-6. Equatorial system of locating
a celestial body
FM 6-2
7-4. ASTRONOMIC TRIANGLE
Figure 7-8. Three sides of the PZS triangle
a. In FA survey, the determination of astro azimuth is based
on the solution of a spherical triangle, a triangle located on
the celestial sphere. The celestial spherical triangle has the
vertices of the pole (P), the observer’s zenith (Z), and the
sun or star (S). This triangle is known as the astronomic,
or PZS, triangle (See Figure 7-7.)
b. The sides of the PZS triangle are segments of great
circles passing through any two of the vertices. Hence, the
sides are arcs and are measured with angular values. The
angular value of each side is determined by the angle that
the side subtends on the earth. (See Figure 7-8.) The three
sides of the PZS triangle are the polar distance, the coaltitude,
and the colatitude.
(1) Polar distance. The side of the PZS triangle from
the celestial North Pole to the celestial body is called the
polar distance (See Figure 7-9.) The value of the polar
distance side is determined from the declination of the
celestial body observed. Declination may be defined as the
angular distance from a celestial body to the celestial equator.
When the celestial body lies north of the celestial equator,
the declination is plus. When the body lies south of the
celestial equator, the declination is minus. The polar distance
side is determined by algebraically subtracting the declination
of the celestial body from 1,600 mils.
Figure 7-7. PZS triangle
Figure 7-9. Polar distance side of the PZS triangle
7-5
FM 6-2
(2) Coalitude. The side of the PZS triangle from the
celestial body to the zenith is called coaltitude. (See Figure
7-10.) The coaltitude is the arc distance from a celestial
body to the observer’s zenith (zenith distance). This arc
distance value is determined by subtracting the observed
altitude of the celestial body (the sun corrected for refraction
and parallax and stars corrected only for refraction) from
1,600 mils.
Figure 7-10. Coaltitude side of the PZS triangle
7-6
FM 6-2
(3) Colatitude. The colatitude is the side of the triangle
extending from the celestial North Pole to the zenith. (See
Figure 7-11.) It is determined by subtracting the latitude of
the observer from 900 (1,600 roils) when the observer is in
the Northern Hemisphere. If the observer is in the Southern
Hemisphere (that is, from 0° to 900 south), the colatitude
is 90° (1,600 roils) plus the amount of south latitude.
Figure 7-11. Colatitude side of the PZS triangle
c. The three angles formed by the three sides of the PZS
triangle are the pallactic angle; the zenith, or azimuth angle;
and the time angle (angle t). (See Figure 7-12.)
(1) The interior angle at the celestial body formed by
the intersection of the polar distance side and the coalititude
side is called the parallactic angle. It is used in determining
azimuth by the arty astro] method but cancels out in the
computations.
(2) The interior angle at the zenith formed by the
intersection of the coaltitude side and the colatitude side is
referred to as the zenith, or azimuth angle. This angle is
the product of the computations and is used to determine
true azimuth from the observer to the celestial body. When
the celestial body is in the east, the azimuth angle is equal
to the true azimuth. When the celestial body is in the west,
true azimuth equals 6,400 roils minus the azimuth angle.
(3) The interior angle of the PZS triangle formed at the
pole by the intersection of the polar distance side and the
colatitude side is called the time angle, or angle t.
Figure 7-12. Three angles of the PZS triangle
d. If the artillery surveyor knows any three elements of the
PZS triangle, the other elements can be determined by
spherical trigonometry. The element the artillery surveyor
always solves for is the angle from the pole to the celestial
body measured at the zenith (azimuth angle). This angle is
used in establishing a true azimuth on the ground. Once the
artillery surveyor becomes familiar with the procedures for
measuring and recording the field data necessary to solve
the azimuth angle of this triangle, he finds that the solution
is no more difficult than solving a plane triangle established
on the earth’s surface. Therefore, the artillery surveyor must
understand how to obtain the essential astro field data.
Obtaining these data requires a limited knowledge of star
identification and how to use the Army ephemeris and DA
forms designed to simplify the solution of the various
formulas.
e. Since each PZS triangle is constantly changing because
of the apparent rotation of the celestial sphere, the solution
for the unknown must be related to specific time. Therefore,
accurate time becomes a highly significant consideration in
astro survey operations.
7-7
FM 6-2
7-5. TIME
a. All astro observations are made on celestial objects that
are in constant apparent motion with respect to the observer.
To make use of these observations and to solve the PZS
triangle, the surveyor must have one other factor. He must
know the precise time of the observation so that he can fix
the position of the terrestrial or horizon system of coordinates
in relation to the celestial coordinate system. In the field of
practical astronomy, two categories of time are used. These
are sun (or solar) time and star (or sidereal) time.
b. Both classes of time are based on one rotation of the
earth with respect to a standard reference line. Because of
the motion of the earth in the plane of its orbit around the
sun once each year, this reference line to the sun is continually
changing (Figure 7-13) and the length of the solar day is
not the true time of one rotation of the earth on its axis.
For the purpose of practical astronomy, the true rotation of
the earth is based on one rotation of the earth on its polar
axis with respect to the vernal equinox and is known as the
sidereal day. Therefore, the lengths of the sidereal day and
the solar day differ. The solar day is longer by 3 minutes
and 56 seconds. The FA surveyor does not have to understand
this differential in the lengths of the solar and sidereal days
to compute azimuth data derived from astro observations.
However, he will be more effective if he does, because he
can then more readily adjust to the continually changing
view of the stars overhead. The explanation of the differential,
while it is simple, requires a departure from the concepts
of a motionless earth and a revolving celestial sphere and
sun. Instead, the concept of a motionless celestial sphere
with the sun as the center and the earth in motion is used
as the basis for the explanation.
e. Since the earth completes one orbit of the sun in 365
and a fraction days, it may be stated that because of the
orbital motion of the earth, the sun has an apparent eastward
motion among the stare of about 1° per day. This motion
of the sun makes the intervals between the sun transits of
the observer’s meridian about 4 minutes greater than the
interval between transits of the VE of the observer’s meridian.
Therefore, the solar day is nearly 4 minutes longer than the
sidereal day. (See Figure 7-13.)
d. Because for purpose of practical astronomy one apparent
rotation of the celestial sphere is completed in a sidereal
day, a star rises at nearly the same sidereal time throughout
the year. On solar time, it rises about 4 minutes earlier from
night to night, or 2 hours earlier from month to month.
Thus, at the same hour, day by day, the stars move slowly
westward across the sky as the year lengthens.
Figure 7-13. Solar day-sidereal day comparison
7-8
FM 6-2
7-6. SOLAR TIME
a. The solar day, or the time corresponding to one rotation
of the earth with respect to the direction of the sun, is the
most natural unit of time for ordinary purposes. If time was
regulated by stars, sidereal noon would occur at night during
half the year. For obvious reasons, this would not be a
satisfactory condition. Also, to begin the solar day when
the sun crosses the observer’s meridian would result in
confusion. So to keep an orderly scheme of things, we start
the solar day when the sun crosses the lower meridian of
the observer. The instant of time when the sun is on the
lower branch of the observer’s meridian is defined as solar
midnight. When the sun crosses the upper branch of the
observer’s meridian, it is solar noon at the observer’s location.
This arrangement would be satisfactory except that the solar
day varies in length. This is because the rate at which the
sun moves along the ecliptic is inconsistent and the orbital
path of the earth around the sun is elliptical. This deviation
in the length of the solar day varies from season to season,
which makes using this variable day as a base for accurate
time almost impossible. Modem conditions demand accurate
measurement of time. Therefore, the mean solar day, an
invariable unit of time, was devised. It is based on a fictitious,
or mean, sun which is imagined to move at a uniform rate
in its apparent path about the earth. It makes one apparent
revolution around the earth in 1 year, as does the actual
sun. The average apparent solar day was used as a basis
for the mean solar day. The time indicated by the position
of the mean sun is called mean solar time. The time indicated
by the position of the actual sun is called apparent solar
time. The difference between the two times is called the
equation of time, and it varies from minus 14m (mean sun
fast) to plus 16m (mean sun slow), depending on the season
of the year. (See Figure 7-14.)
b. The year defined by the fictitious, or mean, sun (tropical
year) is divided into 365.2422 mean solar days. Time based
on these days of constant length is called mean solar time,
or civil time. Since the mean sun appears to revolve around
the earth every 24 hours of mean time, the apparent rate of
movement of the mean sun is 15° of arc, or longitude, per
hour (360 + 24 = 15).
it arrives at the Greenwich meridian. Therefore, the
difference in local time between two places equals the
difference in longitude between the places. (See Figure 7-15.)
To further expedite time conversions, two basic reference
meridians have been selected as common references. These
are the Greenwich meridian and the 180th meridian. The
main classes of time used by the artillery surveyor in his
use of practical astronomy are, in some manner, related to
these basic reference meridians. Subsequent definitions and
explanations make use of these basic reference meridians.
Figure 7-14. Mean and apparent solar time
Figure 7-15. Apparent motion of the sun
c. In the geographic coordinate system (latitude and
longitude), the primary and secondary planes of reference
are the earth equator and the meridian that passes through
Greenwich, England (the prime meridian), respectively.
When the Greenwich meridian is used as a basis of reference,
time at a point 15° west of the Greenwich meridian is 1
hour earlier than the time at the Greenwich meridian, because
the sun passes the Greenwich meridian 1 hour before it
crosses the meridian lying 15° to the west. The opposite is
true of the meridian lying 15° to the east, where time is 1
hour later, since the sun crosses this meridian 1 hour before
7-9
FM 6-2
d. Since the mean solar day has been divided into 24 equal
units of time, there are 24 time zones, each 15° wide, around
the earth. With the Greenwich meridian, 0° longitude, used
as the central meridian of a time zone and the zero reference
for the computation of time zones, each 15° zone extends
7.5° east and west of the zone central meridian. Therefore,
the central meridian of each time zone, east or west of the
Greenwich meridian, is a multiple of 15°. For example, the
time zone of the 90° meridian extends from 82°30' to 97°30'.
(See Figure 7-16.) Each 15° meridian, or multiple of, east
or west of the Greenwich meridian is called a standard time
meridian. Four of these meridians (75°, 90°, 105°, and 120°)
cross the United States. (See Figure 7-17.)
the observer is located. Therefore, LMT is clock time in
the area unless the area is using nonstandard time such as
daylight saving time.
Figure 7-16. Time zone boundaries
e. Standard time zone boundaries are often irregular,
especially over land areas. Standard time zone boundaries
follow the 7.5° rule to each side of the zone central meridian,
approximately, having been shifted wherever necessary to
coincide with geographical or political boundaries. Standard
time, a refinement of mean solar time, is further identified
by names and/or letter designations. For example, the central
standard time (CST) zone, time based on the 90° meridian,
is also the S standard time zone. (See Figure 7-18.) The
artillery surveyor uses the term focal mean time (LMT) in
referring to standard time. It refers to the standard time in
the referenced locale. Local mean time in artillery survey
operations means the standard time for the area in which
Figure 7-17. United States standard time zones
7-10
C1, FM 6-2
f. To preclude the problem of compiling time data for
Note. When local time for an area of o ration is
each of 24 standard time zones of the world, it was decided
unknown or suspect, use universal time Zulu time)
to compute time data pertaining to mean solar time for
and a time zone correction of O hours. When the
only one of the standard time zones. Standard time zone
prompt is for time zone letter instead of time zone
correction, use “Z.” Universal time can be obtained
Z (Figure 7-18), which uses the Greenwich meridian as
from the survey time cube, GPS, or the SPCE.
its basic time meridian, was the zone chosen. Greenwich
standard time, also known as Greenwich mean time (GMT)
or Universal time, is defined as the length of time since
the mean sun last crossed the 180th meridian (lower branch
of the Greenwich Meridian) or solar midnight. This time
can be expressed as the reading of the standard 24-hour
clock at the Greenwich Observatory, Greenwich, England,
at the moment an observation is made on a celestial body;
hence, it is the same time throughout the world. Therefore,
since the observer’s watch is usually set on the standard
time observed in his area, that time (LMT) must be
converted to GMT. The data published in FM 6-300 are
tabulated with respect to the Greenwich meridian and Oh
Greenwich time.
Figure 7-18. World time zone map
7-11
C1, FM 6-2
g. To convert local mean time to Greenwich mean time
when the observer is located in west longitude, divide
the value of the central meridian of the time zone in
degrees of longitude by 15°. This equals the time zone
correction in hours. Add to the LMT the difference in
time between the standard time zone of the observer’s
position and GMT to determine the GMT of observation.
(See Figure 7-19.) If the result is greater than 24 hours,
drop the amount over 24 hours and add 1 day to obtain
the Greenwich time and date. When the observer is
located in east longitude, subtract the time difference
from the LMT to determine the Greenwich mean time
of observation. If subtraction cannot be performed, add
24 hours to the LMT and drop 1 day to determine the
Greenwich date of observation.
h. When the artillery surveyor makes observations on the
sun, obviously he observes the apparent sun instead of the
mean sun on which his time is based. Consequently, the
observer must convert the Greenwich apparent time (GAT)
of observation to the GMT. The date of observation is used
as an argument to enter Table 2 of FM 6-300, and the value
of the equation of time for zero hours GMT (O h) is extracted
along with the daily change. The resultant equation of time
value for the date and time of observation is then added
algebraically to the GMT of observation.
i. Determining the local hour angle (LHA) of the sun, a
value necessary for some astro formulas, requires several
steps in addition to those in the example above. When the
position of the apparent sun at the time of observation has
been determined and related to the Greenwich meridian, the
time is referred to as Greenwich apparent time. By simply
adding 12 hours to, or subtracting it from, the GAT (the
result cannot exceed 24 hours), the surveyor determines the
value of the Greenwich hour angle (GHA). The Greenwich
hour angle is the amount of time that has elapsed since the
sun last crossed the Greenwich upper meridian. The next
step is to convert both the observer’s longitude, extracted
from a trig list or scaled from a map, and the Greenwich
hour angle to mils of arc. The arc distance (in mils) measured
from the Greenwich meridian to the observer’s meridian is
added to the GHA in roils if the observer is located in east
longitude. It is subtracted from the GHA in mils if he is
located in west longitude. The result is the local hour angle
of the apparent sun expressed in mils of arc. The final step
is to determine angle t, the angle at the polar vertex of the
PZS triangle, Angle t is determined as discussed below,
(1) If the local hour angle is greater than 3,200 mils,
angle t equals 6,400 mils minus LHA.
(2) If the local hour angle is less than 3,200 mils, angle
t equals LHA.
Figure 7-19. Application of the time zone correction to local mean time to obtain Greenwich mean time
7-12
FM 6-2
7-7. SIDEREAL TIME
a. The sidereal day is defined by the time interval
between successive passages of the vernal equinox over
the upper meridian of a given location. The sidereal year
is the interval of time required for the earth to orbit the
sun and return to its same position in relation to the
stars. Since the sidereal day is 3 minutes 56 seconds
shorter than the solar day, this differential in time results
in the sidereal year being 1 day longer than the solar
(tropical) year, or a total of 366.2422 sidereal days. Since
the vernal equinox is used as a reference point to mark
the sidereal day, the sidereal time for any point at any
instant is the hours, minutes, and seconds that have
elapsed since the vernal equinox last passed the meridian
of that point.
b. In general, it can be stated that observations on the
sun involve apparent solar time, whereas observations on
the stars are based on sidereal time. The computations
using either apparent solar time or sidereal time are similar
in that they do nothing more than fix the locations of
both the celestial body and the observer in relation to the
Greenwich meridian. Once a precise relationship has been
established, it is a simple matter to complete the determination of azimuth to the celestial body.
Section II
ASTRONOMIC OBSERVATION TECHNIQUES
The technique used to observe a celestial body depends on the azimuth determination method used
(altitude, arty astro observation, or Polaris tabular) and the type of celestial body being observed.
Using the proper techniques will ensure more accurate results.
7-8. PURPOSE OF ASTRONOMIC
OBSERVATIONS
Astro observations can be used for, but are not limited to,
the following survey operations:
the triangle. In addition to the angle from a ground point
to the celestial body, three elements must be determined.
These elements are as follows:
Ž Latitude for determining the side colatitude.
• Determining or checking a starting azimuth for a
conventional survey.
• Declination of the body for determining the side polar
distance.
• Determining or checking the closing azimuth of a
conventional survey.
• Attitude for determining the side coaltitude.
Ž Checking the azimuth of any line in a survey.
Ž Providing orienting azimuths for cannons and associated
fire control equipment.
Figure 7-20. Altitude method of solving the
PZS triangle
• Determining azimuths for the declination of aiming
circles.
• Providing orienting azimuths for radars and OPs.
7-9. METHODS OF DETERMINING
AZIMUTH
The artillery surveyor uses three basic methods to determine
azimuth by astro observation-the altitude method, arty astro
observation, and Polaris tabular method. All three methods
require a horizontal angle from an azimuth mark to the
observed body to materialize the astro azimuth on the ground.
a. In the altitude method (Figure 7-20), the PZS triangle
is solved by using the known data and the three sides of
7-13
FM 6-2
b. In the arty astro method (Figure 7-21), the azimuth
angle is determined from two sides and the included angle.
The sides are the polar distance and colatitude and must be
determined as described in paragraph 7-4b. The angle at P
(Figure 7-21) is angle t. The value of the local hour angle
is computed by using the time of the observation and is
then used to compute angle t.
Figure 7-21. Arty astro method of solving the
PZS triangle
c. In the Polaris tabular method, the azimuth to Polaris
is tabulated in the Army ephemeris for every 3 minutes of
local sidereal time (LST). The listed azimuth is corrected
for the observer's latitude and the date of observation. This
method avoids lengthy PZS triangle solutions, but it can be
used only in the Northern Hemisphere.
Note. The methods of determining azimuth are
discussed in detail and compared in Sections V, VI,
VII, and Vlll.
7-10. FIELD REQUIREMENTS FOR
ASTRONOMIC OBSERVATIONS
a. Each of the three methods of determining azimuth by
astro observation requires the measurement of the horizontal
angle from the azimuth mark to the celestial body. The altitude
method also requires measurement of the vertical angle. (See
Figure 7-22.) Except for the method of pointing on the
celestial body, horizontal and vertical angles are measured
in the same way that angles are measured in traverse. A set
of astro observations consists of horizontal angles measured
one position and vertical angles measured by one direct and
one reverse pointing.
b. In all astro observations, the instrument must be perfectly
level with reference to the most sensitive bubble the
instrument has. An appreciable error, which cannot be
eliminated by direct and reverse pointing, is introduced into
the measurement of a horizontal angle between two objects
of considerable difference in elevation if the vertical axis
of the instrument is not vertical.
7-11. FIELD DATA REQUIREMENTS
Figure 7-22. Measuring horizontal and vertical
angles from azimuth mark to celestial body
Data required for computing astro azimuth differ slightly
according to the method used.
a. Altitude and Polaris tabular methods require the following
data
• Latitude of the observer (correct to the nearest second).
Ž Longitude of the observer (correct to the nearest second).
• Horizontal angle from the desired azimuth mark to the
celestial body.
• Approximate azimuth to the desired azimuth mark. A
magnetic or map-spotted azimuth will suffice.
Ž Date of observation.
b. In addition to the data in a above, the altitude method
requires the following data:
• Temperature (correct to nearest 50)
• Vertical angle to the celestial body.
7-14
C1, FM 6-2
Time of observation.
– Sun (accurate to the nearest 5 minutes).
– Star (accurate to the nearest day).
c. In addition to the data in a above, the Polaris tabular
method requires time accurate to the nearest minute.
d. The arty astro method of observation requires the
following data:
UTM coordinates (casting and northing) map-spotted to
within 150 meters.
Horizontal reading from the desired azimuth mark to the
celestial body.
Approximate azimuth to the desired azimuth mark. A
magnetic or map-spotted azimuth will suffice.
Date of observation (manual input or BUCS time module).
Time of observation (manual input or BUCS time module).
- Sun (accurate to 1 second).
- Star (accurate to 1 second).
- Polaris (accurate to 10 seconds).
e. Special requirements are discussed below.
(1) For the sun to be suitable for use with the altitude
method, it should be within 530 mils of the observer’s prime
vertical. To determine if it is, algebraically subtract the
declination of the sun on the local date from the latitude of
the observer’s station. The remainder is the angle from the
prime vertical to the sun at noon, When he is observing the
stars, the observer will have little difficulty in selecting stars
that fall within the 530-mil requirement. The celestial bodies
(sun or stars) should be observed between 175 mils and 800
mils in altitude. The sun should not be observed within 2
hours local apparent time of the observer’s meridian, because
there is no valid solution when the coaltitude side of the
triangle is less than 30° (2 hours).
Note. The restriction has been placed on vertical
angles over 800 mils because of the error
introduced into the horizontal angle measurement
when the instrument has not been leveled
perfectly. The error in the horizontal angle is equal
to the tangent of the altitude of the celestial body
multiplied by the error in Ieveling the plate of the
instrument. In the case of the T11 or T2 theodolite,
one division of error in the plate level bubble is
equal to an error of about 0.1 mil if the altitude
angle is 800 mils. If the altitude angle is 1,000 mils,
the error in the horizontal angle will be about 0.2
mil. For this reason, special precautions must be
taken in Ieveling the instrument when a vertical
angle between 800 and 1,100 mils is required.
(2) When the arty astro method is used, the sun should not
be observed within 1 hour local apparent time of the
observer’s meridian. This is because there is no valid solution
when angle t is less than 15° (1 hour).
(3) The selection of Polaris in the Northern Hemisphere or
Alpha Acrux (Southern Cross Star) in the Southern
Hemisphere should be automatic. The altitude of Polaris
roughly coincides with the north latitude of the observer,
Circumpolar stars are preferred to east-west stars.
(4) The arty astro method is the only acceptable method
used with circumpolar stars other than Polaris.
(5) For best results, stars should be below 800 mils in
altitude.
7-12. TEMPERATURE AND TIME
a. Temperature and a time correction should be obtained
at the time of observation and checked after the final
observation. The temperature may be obtained from
meteorological (met) stations, powder thermometers, or any
thermometer available. Time may be obtained from radio
time signals (paragraph 7-32) or from the div arty SPCE.
Message center and commercial radio times are generally
accurate enough for altitude observations.
b. The BUCS contains an accurate quartz-crystal clock.
Properly set, it will keep accurate time, within tenths of a
second, until battery life expires or the memory is cleared.
Any good watch with a sweep second hand is adequate for
timekeeping, if a correction is carried. For astro observation,
a good watch is one that gains or loses a constant amount
of time over a given period. The timekeeper should not try
to set his watch to the exact time, but he must ensure that
the second hand is in the vicinity of 12 when the minute
hand is on a minute mark. (This will preclude a 30-second
error.) The timekeeper will determine the amount his watch
is in error and note the correction, with the proper sign, in
the remarks section of the recorded field notes.
7-13. POINTING TECHNIQUES
a. When the sun is being observed, special pointing
techniques are required to resolve its center because of the
size and brilliance of the sun. Since the angular diameter
of the sun is about 9.5 mils of arc, an accurate pointing
cannot be made on the center of its disk without the use of
special aids and/or techniques.
b. One of the special pointing aids is the solar circle etched
on the reticle of the observing instrument. Most theodolites
have the solar circle etched on the reticle, (See Figure 3-4.)
No special pointing technique is required with these
instruments, but the sun must be centered in the circle. The
sun will not always fit exactly into the circle. However, the
amount of overlap, or spacing, will not affect the final result.
7-15
C1, FM 6-2
c. Pointings on stars are made so the intersection of the
vertical and horizontal cross hairs bisects the star.
7-14. TRACKING AND OBSERVING
PROCEDURES
a. The instrument operator sets up his instrument as
prescribed in Chapter 3. With the instrument telescope in
the direct position, he points the telescope at the azimuth
mark. After the initial circle setting has been recorded in
the recorder’s book, the instrument operator and recorder
perform the steps discussed below.
(1) The instrument operator places the sun filter on the
telescope and turns the instrument until the sun is near the
center of the solar circle. He announces TRACKING.
CAUTION
The sun must never be viewed through the telescope
without a sun filter. The filter should be inspected before
use to ensure that the coated surface is free from
scratches or other defects. Serious eye damage will
result if proper precautions are not taken.
Note. If the sun filter has been damaged or lost, a
solar observation may be completed by use of the
card method. The image of the sun is projected onto
a card held 3 to 6 inches behind the eyepiece, and
the telescope is focused so that the cross hairs are
clearly defined.
(2) on the instrument operator’s announcement of
TRACKING, the recorder begins keeping time without
lifting his eyes from the watch. At the instrument operator’s
announcement of TIP, the recorder notes the exact
uncorrected time and records it in the field notebook. If the
BUCS is being used as a time piece, the recorder presses END
LINE at the announcement of TIP. If the forward entry device,
meteorological/survey (FED MSR) is being used, the use of
the time module is also an option.
(3) The instrument operator reads the horizontal circle
reading and announces it to the recorder, levels the split
bubble, and announces the vertical circle reading.
Note. Vertical angles are not measured for the arty
astro or Polaris tabular methods.
(4) The instrument operator then plunges the telescope
to the reverse position, again sights on the sun, and announces
TRACKING. The steps in (2) and (3) above are then
repeated. The observer then sights on the azimuth mark and
reads the horizontal circle reading. The recorder records the
reading and determines the mean data. This completes one set
of observations.
7-16
Note. When using the arty astro method of
observation, the instrument operator takes three
direct readings to the celestial body, then plunges the
telescope, and sights back on the azimuth mark. A
second set should be taken with three readings in the
reverse position as a check on the instrument and
operator. As a rejection criteria, the closing readings
on the azimuth mark should agree with the initial
circle setting by the known spread of the instrument.
In addition, the mean of the two sets of readings
should agree with both sets within prescribed
accuracies.
b. Three sets of observations must be made normally by
the procedures in a above. However, a well-trained observer
may use a modified form of these procedures. A modified
form would be to take three direct observations and then
three reverse observations before closing the angles on the
azimuth mark. Care must be taken in recording the
observations.
c. Pointings on the stars are made in the same manner as
pointings on the sun except that at the instant TIP is
announced the cross hairs should bisect the star.
Note. When the observer is observing the stars, it is
advantageous for him to have the telescope blacked
out until the star is identified. When the star has been
identified, the telescope light rheostat is turned up so
that as many stars as possible, other than the desired
one, will be obliterated by the light in the telescope.
7-15. RECORDING AND MEANING DATA
a. The format for recording field data and determining the
mean angles is generally the same as that for other angle
measurements except for the large spread between the direct
and reverse readings and that the times of observation are
recorded. The mean time of observation is determined from
the times recorded for the direct and reverse pointing. The
same format is used for observations with the T16 and T2
theodolites. Sun observations are recorded in the same manner
as star observations, Figures 4-12, 4-13, 4-15, and 4-20 show
how data are recorded in a field notebook for astro
observations.
b. Extreme care must be taken in meaning time. Time is
recorded in three units-hours, minutes, and seconds. If using
a watch to record time, record seconds first, followed by
minutes and hours. Time should be meaned by using the
method described in the following example.
FM 6-2
7-17
FM 6-2
Section Ill
THE ARMY EPHEMERIS
The Army ephemeris (FM 6-300) is a condensation of data from the American Ephemeris and
Nautical Almanac. Units must request FM 6-300 from the AG Publications Center or be on pinpoint
distribution. It is issued to artillery units equipped to perform astro observations. Data in the tables
of FM 6-300 are required in computing direction from astro observations. All data extracted from
the ephemeris tables will be expressed to the accuracy of the ephemeris. The use of the ephemeris
tables is explained in this section. Sample problems are based on data in the ephemeris for 1993
through 1997. Only the tables used by the artillery surveyor are explained herein.
7-16. TABLE 1b, ASTRONOMIC
REFRACTION CORRECTED
FOR TEMPERATURE (MILS)
7-17. TABLE 2, SUN (CURRENT YEAR)
FOR ZERO HOURS UNIVERSAL
TIME (GMT)
a. Table 1b of FM 6-300 is used to determine the value of
the refraction correction. This correction is applied to vertical
angles measured to either the sun or the stars. Refraction
is the apparent displacement of a celestial body caused by
the bending of light rays passing through layers of air of
varying density. The celestial body appears higher than it
really is. Therefore, the sign of the correction is always
minus.
Table 2 is divided into three major parts-apparent
declination (shown in both degrees and mils), equation of
time, and sidereal time. Each of the major parts is discussed
separately. The first column is common to all three parts
of Table 2 and contains the Greenwich dates and days of
the week for the entire year.
b. To determine the value of the refraction correction,
use as arguments the mean vertical angle (observed
altitude) and the mean temperature at the time of
observation. Arguments for temperature increase in units
of 10° from -30°F to + 130°F. Arguments for observed
altitude increase in units of 10 roils from 0 roils through
1,200 mils. When the observed altitude and temperature
are not tabulated in the table, enter the table with the
values nearest those observed. For example, to determine
the refraction correction for a mean vertical angle of 697
roils and a temperature of +93°F at the time of observation,
examine the table. The nearest tabulated altitude is 700
roils, and the nearest temperature is +90°F. Enter the table
at 700 roils, and move right to the column for 90°F. Extract
the refraction correction of 0.32 mil. Should the mean
vertical angle fall exactly halfway between two tabulated
altitudes, use the higher tabulated altitude. Should the
temperature fall exactly halfway between two tabulated
temperatures, use the lower tabulated temperature. For
example, to determine the refraction correction for a mean
vertical angle of 745 mils, which is halfway between two
tabulated altitudes (740 mils and 750 mils), select the
higher value (750 mils). For a temperature of 95°, halfway
between two tabulated temperatures (+90° and +100°),
select the lower (90°). Extract the refraction correction
of 0.29mil.
7-18
a. Apparent Declination. The declination of a celestial
body is the angular distance from the celestial equator
measured along the hour circle of the body. Declination,
which is positive when the body is north of the celestial
equator and negative when it is south of the celestial equator,
corresponds to latitude on earth. The declination of the sun
is tabulated for 0 hours GMT for each day of the year, and
the daily change in declination is shown in the DAILY
CHANGE (SEC) column. The algebraic signs of the
declination and the daily change are critical and must be
included. When the BUCS is used, the value of apparent
declination in degrees, minutes, and seconds is determined
to the nearest second.
b. Sidereal Time. The local sidereal time is the number
of hours, minutes, and seconds that have elapsed since the
vernal equinox last crossed the observer’s meridian. The
Greenwich sidereal time is the hours, minutes, and seconds
that have elapsed since the vernal equinox last crossed the
Greenwich meridian. Sideral time is used when Polaris
tabular observations have been made and it is necessary to
convert mean time to sidereal time. The sidereal time to the
nearest second is extracted from Table 2.
7-18. TABLE 9, ALPHABETICAL
STAR LIST
Table 9 is an alphabetical list of 73 stars, the constellation
in which each star is found, the number of each star, and
FM 6-2
the magnitude of each star. This table is used primarily to
provide the star numbers to determine data on the stars from
Table 10. The constellation and magnitude aid in identifying
the star. For example, find the star Enif in the list. The table
shows that Enif is in the constellation Pegasus, is star number
70, and has a magnitude of 2.5.
hours GMT on the 0, 10th, 20th, and 30th days of each
month (10-day) intervals). To determine the declination or
the right ascension of Polaris for a given day, interpolate
between the given values. Data for the 31st day of the month
are shown as the0 day of the following month.
7-19. TABLES 10a (DEGREES) AND
10b (MILS), APPARENT PLACES
OF STARS
Tables 10a and 10b contain the declination for all the stars
listed in Table 9 except Polaris. In Table 10a declination
is in degrees. Table 10b lists declination in mils. Right
ascension and declination are given for the first day of each
month. Values for other dates are interpolated as discussed
below.
a. Determine the difference for both right ascension and
declination (in seconds) from the first of the month to the
first of the following month. Use the proper algebraic sign.
b. Divide the number of days past the first of the month
by 30 days (standard month). Multiply the result by the
difference determined in a above to obtain the changes in
right ascension and declination from the first of the month.
c. Apply the change determined in b above to the declination
at the first day of the month to determine the declination
for the given day.
7-21. TABLE 12, TO DETERMINE
AZIMUTH FROM POLARIS
The artillery surveyor uses Table 12 only to determine
azimuth by the Polaris tabular method. Correct time should
be known to the nearest 1 minute.
a. Extraction of b0. The argument used for extracting b 0
is local sidereal time and current year. The hours of local
sidereal time are listed in column headings across the page,
and the minutes of LST are listed vertically at the left of
the hour columns.
7-20. TABLE 11, APPARENT PLACES
OF POLARIS (STAR NUMBER 10)
Table 11 contains the declination (in degrees and mils) and
the right ascension of Polaris. The values listed are for 0
b. Extraction of b1. The arguments used to extract b 1 are
the same hour column used to find
and the observer’s
latitude.
7-19
FM 6-2
for b0 and b1) and Greenwich date. From the 1st to the
15th day of the month, use the Greenwich month of
observation. From the 16th to the last day of the month,
use the month after the Greenwich month of observation.
7-22. TABLE 13, GRID AZIMUTH
CORRECTION, SIMULTANEOUS
OBSERVATION
c. Extraction of b2. Find the value of b 2 by entering the
bottom section of the table with the hour (same column as
Table 13 is a nomograph for determining the grid azimuth
correction in a simultaneous observation. Use of this table
is explained in Section IX of this chapter.
Section IV
STAR SELECTION AND IDENTIFICATION
There are important advantages to using stars rather than the sun as sources of astro azimuth. Since
they appear as pinpoints of light in instrument telescopes, stars are easier to track than the sun.
At least one of the 73 stars tabulated in the Army ephemeris can usually be found in a satisfactory
position for observation regardless of the time of night or the observer's latitude. The North Star
(Polaris) should always be used when the geographical location and tactical situation permit. Polaris
is the most desirable source of astro azimuth because it is easily identified and bcause its slow
apparent motion makes it easy to track. The Polaris tabular method yields reliable azimuths in
considerably less time than any other method. In the low northern latitudes and the Southern
Hemisphere, however, east-west (noncircumpolar) stars must be used for night astro azimuth
determination. Local weather conditions obscuring Polaris may also make observation of east-west
stars necessary. Since so many stars are available for observation, the artillery surveyor must be
able to select and identify those most suitable for observation. The star finder and identifier is
used to identify them.
7-23. STAR FINDER AND IDENTIFIER
The star tinder and identifier (Figure 7-23) is a device used
to determine the approximate (±2°) azimuth and altitude of
a given star. This device is issued as a component of the
survey set, artillery fire control, fourth-order. The star finder
and identifier consists of a base, 10 templates, and a carrying
case. The base is reversible with stars of the Northern
Hemisphere on one side and stars of the Southern Hemisphere
on the other. There is one template for each 10° of latitude
from 5° to 85° (5°, 15°, 25°, 35°, and so forth). (The tenth
template, designed for plotting the sun and planets, is not
used in artillery survey). Each template is reversible with
one side for north latitude and the other side for south latitude.
The template constructed for the latitude nearest the latitude
of the observer should be used. The base of the star finder
in Figure 7-23 shows the stars visible in the Northern
Hemisphere. The center of the device represents the celestial
North Pole. The edge of the base is a circle graduated in
degrees and half degrees, representing the local hour angle
7-20
of the vernal equinox or the local sidereal time. On each
template is a series of concentric ellipses. Around the outer
edge of these ellipses are two sets of numbers from 0° to
360°. The inner set of numbers starts at the top of the template
for north latitude and increases in a clockwise direction.
The outer set of numbers starts at the bottom of the template
for south latitude and increases in a clockwise direction
around the ellipses. In the Northern Hemisphere, the inner
figures are used; in the Southern Hemisphere, the outer figures
are used. The inner set of figures represents the azimuth
from the celestial North Pole to the line that the figures
identify. The outer set of figures represents the same thing
except that the azimuth is from the celestial South Pole to
the line. The series of concentric ellipses represents altitudes
above the horizon. The template has the horizon on its
circumference, the zenith as its center, and a measure of
azimuth around the edge. The 0° to 180° line represents the
observer's meridian. Before the star finder can be oriented,
the value of the local sidereal time must be determined. The
pointer of the template is then placed over the appropriate
FM 6-2
value on the base of the star limier. Local sidereal time
can be determined by using DA Form 7284-R (Computation
of Star Identification (BUCS)) or by using the Haught
method for orienting the star finder and identifier. (A
reproducible copy of DA Form 7284-R is included at the
back of this book.)
Figure 7-23. Star finder and identifier
7-21
FM 6-2
7-24. HAUGHT (FIELD-EXPEDIENT)
METHOD FOR ORIENTING THE
STAR IDENTIFIER
This is a simple method of computing the LST for orienting
the star finder and identifier. The results are accurate to
within 1° and can be used for any time or location. The
final result is the LST for 1900 on the date of observation.
Use the time-arc relationship to adjust for different
observation times. One hour is equal to 15° of shift on the
star finder and identifier, and 4 minutes is equal to 1° of
shift. To compute the LST by using the Haught method,
follow the procedures discussed below.
a. Count the number of months this year preceding the
observation month. Multiply that number by 30.
b. Add the observation date.
c. Add a constant of 24.
d. Determine the difference between the observer’s longitude
and the longitude of the central meridian of the observer’s
time zone. Add the difference if the observer is east; subtract
if west.
e. If using daylight saving time (DST), subtract 15. DST
in the US is from the first Sunday in April to the last Sunday
in October. The result is the LST (orienting angle) to set
on the star identifier for 1900.
f. Determine the difference between 1900 and the time of
observation. (Each hour is equal to 15°, and each 4 minutes
is equal to 10.) Add if the observation time is after 1900,
and subtract if the observation time is before 1900.
7-25. SELECTION OF STARS FOR
OBSERVATION
a. The apparent motion of a celestial body has two
components-a horizontal motion, representing change in
azimuth and a vertical motion, representing change in
altitude. An error in measuring the altitude of a celestial
body will result in a final azimuth error related to the ratio
between the two components of the apparent motion of the
body. (See Figure 7-24.) When a star is moving at a small
angle to the horizon, an error in measuring the altitude will
result in a greater error in final azimuth than it would if
the star were moving at a large angle to the horizon. (See
Figure 7-25.) This relationship is called the star rate, which
is the ratio of resulting azimuth error to error in vertical
measurement. A star that changes in altitude but not in
azimuth will have a star rate of 0, since an error in altitude
measurement will result in no error in azimuth. A star that
changes so rapidly in azimuth and so slowly in altitude that
a 1-mil error in attitude measurement will result in a 3-mil
azimuth error has a star rate of 3.
b. For altitude method observations, select the stars with
the lowest star rates, since both azimuth and altitude are
measured. Low star rates are not essential for arty astro
observations, because altitude is not measured. However,
stars with low star rates will be moving more slowly in
azimuth and will be easier to track than those with high
star rates. Although Polaris has a high star rate in its
culminations, its apparent motion is so slow that it can be
observed successfully at any time. Avoid observing stars
below 175 roils in altitude because of possible errors caused
by refraction.
Figure 7-24. Motion of a star viewed through a
surveying instrument—high star rate
7-22
FM 6-2
Figure 7-25. Motion of a star viewed through a
surveying instrument—low star rate
Figure 7-26. World star chart
7-26. WORLD STAR CHART
a. A map depicts the prominent points on the earth, and
the star chart depicts the prominent points in the sky. (See
Figure 7-26.) On the earth latitude and longitude are used
to fix the location of points; declination and right ascension
are generally used to fix the stare at definite coordinates,
Consequently, on a star chart the north-south location of a
star is fixed by declination, and the east-west location is
fixed by right ascension.
b. The two projections by which star charts are plotted are
cylindrical (similar to the mercator projection for world maps)
and plane (similar to polar projection for world areas). The
cylindrical projection presents great distortion about the poles
of the celestial sphere but offers a fairly accurate picture in
declination to ±65°, It should be remembered that in such
a projection the vertical lines plotted to be parallel actually
converge at the poles and are perpendicular to the equator.
The plane projection presents a truer picture of the sky,
especially if it is used with a mark that blocks out all the
sky except that within the horizon for a given area.
c. The brightness of stars is measured in magnitude. Thus,
the brightest stars are of the first magnitude, the next in
brightness are of the second magnitude, and so forth. Stars
in constellations, some of which have individual names (for
example, Polaris), are usually named in the constellation in
order of their brightness through the use of the Greek alphabet.
Thus, in the constellation Orion, from the brightest to the
least bright, the stars are named a (Betelgeuse [also
Betelgeux]), (Rigel), (Bellatrix), and so forth. The
magnitude of each star is shown on star charts.
7-23
7-23 FOLDOUT
FM 6-2
(a) Enter the table with the closest date of observation.
(3) Hold the world star chart with the word North on
top. Locate the graduation at the top the chart that represents
the LST. Face south, and align the LST graduation just below
the celestial equator along the observer’s meridian. The world
star chart is now oriented with the stars in the sky.
(b) From the date, move to the right and stop in the
column of the closest hour of observation.
e. The following method can be used to orient the world
star chart in the Southern Hemisphere.
d. The following method can be used to orient the world
star chart in the Northern Hemisphere.
(1) Determine the LST of observation from Figure 7-27.
(1) Determine the LST from Figure 7-27 by using the
same procedures in subparagraph d.
(c) Extract the LST from the hour column.
(2) Locate the celestial equator.
(a) Subtract the observer’s latitude from 90°. The result
is the distance above the horizon to the celestial equator.
(b) Facesouth, and determine the position of the celestial
equator. Remember, at arms length, a finger width is 2°, 1 hand
width is 10°, and 1 hand span is 20°.
Figure 7-27. Local sidereal time
DATE
7-24 FOLDIN
EVENING
HOURS
MIDNIGHT
MORNING
HOURS
2000
2400
0400
(2) Locate the celestial equator. This is done the same
as in the Northern Hemisphere except the observer must
face north and count up from the horizon to locate the celestial
equator.
(3) Hold the world star chart with the wo South at
the top. Locate the graduation at the top of the chart that
represents the LST. Face north, and align the LST graduation
just below the celestial equator along the observer’s meridian.
f. To aid the observer, highlight the 30 0N and W S lines
on the star chart. Also highlight the 0 0 line, which is the
celestial equator. The strip of sky as outlined by the 30 0N
and 300S lines will contain the brightest stars (seen at any
one time). Keep in mind that the strip of sky being looked
at is about 6 hours either side of the LST.
JAN 5
20
3
4
7
8
11
12
FEB 4
20
5
6
9
10
13
14
MAR 7
22
7
8
11
12
15
16
APR 7
22
9
10
13
14
17
18
MAY 7
22
11
12
15
16
19
20
JUN 7
22
13
14
17
18
21
22
JUL 7
22
15
16
19
20
23
0
AUG 7
22
17
18
21
22
1
2
SEP 7
21
19
20
23
0
3
4
OCT 6
21
21
22
1
2
5
6
NOV 6
21
23
0
3
4
7
8
The easiest way to identify stars and fix their locations in
relation to each other is to learn something about
constellations. Since stars are fixed in definite points in the
sky with relation to each other, the relative position of stars
has remained about the same for many centuries. In certain
groups of stars, primitive stargazers saw the shapes of
creatures or heroes of their folklore. Names were applied
to the shapes of these various groups of stare. Later, people
saw in the stars the shapes of household implements with
which they worked. The development of the names of stars
began early in the history of man and finally resulted in a
catalog of the visible stars. The named shapes became
constellations, and the individual stars were identified by
name with the constellation of which they were a part. From
this primitive development the constellations were given
Latin names. Other groups of stars were assigned names of
gods and goddesses and creatures of land and sea that figured
in Roman and Greek mythology. Much later in history, our
forefather saw in the many constellations objects common
to their mode of living. Thus, the Big Bear came to be
known as the Big Dipper. To the English, this same
constellation is the Plough. Some of the more familiar starts
and constellations are described below.
DEC 6
21
1
2
5
6
9
10
a. The familiar constellation called the Big Dipper is only
part of the constellation Ursa Major. (See Figure 7-28.) The
7-24
7-27. LOCATING STARS
FM 6-2
seven stars of the dipper are easy to find on almost any
clear night. The two outer stars of the bowl point toward
the North Star, Polaris, which is about 30° away. The distance
between the pointers is about 5°. Both measurements are
very helpful when the star finder and identifier is being
used.
c. Polaris, the polestar, is the alpha star in the constellation
Ursa Minor (Figure 7-30), commonly called the Little Dipper.
On a clear night, the Little Dipper is easily seen. The handle
of the dipper has a reverse curve, and Polaris is the last star
in the handle.
Figure 7-30. Ursa Minor
Figure 7-28. Ursa Major
b. Cassiopeia (Figure 7-29), sometimes called the Lady in
the Chair, the Running M, or the Lazy W, is a prominent
northern constellation. It is found directly across the celestial
North Pole, opposite the Big Dipper. When the Big Dipper
is below the horizon, Polaris can be found by drawing a
line from the star Ruchbah bisecting the angle formed by
the shallow side in Cassiopeia. The bisecting line points
almost through Polaris.
Figure 7-29. Cassiopeia
d. The first prominent constellation after the vernal equinox
has risen in the east is Taurus, the Bull. (See Figure 7-31.)
On the forehead of Taurus is a red star of the first magnitude,
Aldebaran. It is a royal star, one of the four stars most
commonly used by navigators. On the upper foreleg of Taurus
is the Plaeiades. This aggregation is a tight cluster of stars,
which is also called the Seven Sisters.
Figure 7-31. Taurus
7-25
FM 6-2
e. Chasing these seven stare and the bull is Orion, the Hunter.
(See Figure 7-32.) There are two very bright stars in Orion.
The hunter’s right shoulder is Betegeuse Orionis); his
Orionis). Close on the heels of Orion
left knee is Rigel
are his two dogs, Canis Major and Canis Minor. In the big
dog is the brightest star in the sky, Sirius. It is a brilliant
blue-white star. Slightly behind Canis Major is the smaller
dog in which Procyon is found.
g. About 2 hours behind Gemini and Canis Minor is Leo,
the Lion. (See Figure 7-34.) The head and forequarter of
Leo are sometimes known as the Sickle. The body and tail
extend off to the east. The heart of Leo is Regulus (α Leonis).
Regulus is another of the four royal stare. It is brilliant
white, whereas the others are red.
Figure 7-34. Leo
Figure 7-32. Orion
f. At about the same right ascension with the canine
constellation is Gemini, the Twins. (See Figure 7-33.) Think
of Gemini as a wedge pointed straight toward Orion. The
bright star at the base of the wedge is Pollux (ß Geminorum);
the one above it is Castor (α Geminorum).
Figure 7-33. Gemini
7-26
h. As soon as Leo is well up in the sky, Virgo (Figure
7-35) will rise in the east. The bright star in Virgo, called
Spica (a Virginis). makes an approximately equilateral
triangle with Denebola (ß Leonis) and Arcturus (α Bootis).
This triangle is sometimes called the Virgo triangle.
Figure 7-35. Virgo
FM 6-2
i. One of the most easily recognized constellations is
Scorpio. (See Figure 7-36.) However, it is so far south
that in northern latitudes it is visible during evening hours
only through July and August. Antares (α Scorpii) is
another of the four royal stars.
k. Pegasus (Figure 7-38), which includes the Great
Square, straddles the hour circle of the vernal equinox.
This is the constellation of the flying horse, a very
prominent skymark.
Figure 7-38. Pegasus
Figure 7-36. Scorpio
j. The Northern Cross, Cygnus, is found very close to
the circumpolar region. (See Figure 7-37.) This is a very
prominent constellation, and in northern latitudes in the
fall, it will be nearly overhead in the evening. The head
of the cross is Deneb (α Cygni). There are two neighbor
stars in this sector of the sky-Vega (α Lyrae), which
rises just before the cross, and Altair (α Acquilae), which
trails it somewhat to the south. Cygnus is imagined by
some to be a cross; to others, it takes the shape of a
swan from which the name is derived.
Figure 737. Cygnus
l. Fomalhaul, the fourth royal star, is a prominent star
in the southern sky. It ranks number 13 in brightness
of stars visible in the Northern Hemisphere.
7-28. STAR IDENTIFICATION (BUCS)
Approximate azimuth and altitude to a selected survey
star at a date and time chosen by the user can be
determined by using DA Form 7284-R (Figures 7-39 and
7-40) and Program 7 of the SURVEY REV1 module.
This orientation data will help identify survey stars for
astro observation or navigation.
a. Capabilities. This program will compute the
approximate azimuth and altitude (vertical angle) to
any of the 73 survey stars selected by the user. These
orientation data are accurate to ±5.0 roils for the date,
time, and location selected for observation. The user
can determine orientation data for any number of
survey stars with the program, but he is limited to six
sets of data per form. This program will enhance the
surveyor’s ability to identify stars in the Northern and
Southern Hemispheres. It provides a tool for leaders
to train surveyors to respond rapidly to astro
observation requirements.
b. Program and Form Instructions. See Table 7-1 for
instructions on computing DA Form 7284-R by using
Program 7 of the SURVEY REV1 module.
7-27
FM 6-2
Figure 7-1. Instructions for computing DA Form 7284-R
7-28
FM 6-2
Table 7-1. Instructions for computing DA Form 7284-R (continued)
7-29
FM 6-2
Figure 7-39. Sample DA Form 7284-R
7-30
FM 6-2
Figure 7-40. Reverse of DA Form 7284-R
7-31
FM 6-2
Section V
ALTITUDE METHOD
The altitude method can be used to determine azimuth from the sun or from the stars. This method
requires the solution of the astronomic (PZS) triangle (Figure 7-20) by using, as determined data,
the three sides of the triangle (polar distance, colatitude, and coalititude). In the altitude method,
the time is required only to determine the declination of the body. When the sun is observed, the
time should be accurate within 5 minutes. For stars, only the date is required. Since time is not
critical in the altitude method of observation, this method is used most frequently by artillery
surveyors.
7-29. POSITIONS OF CELESTIAL
BODIES
Stars for altitude observation should be in the east or west
between 175 and 800 roils in altitude. When the sun or a
star is observed, it should be within 530 mils of the observer’s
prime vertical. This is the arc on the celestial sphere that
passes through points due east and west of the observer and
through his zenith. The sun must not be within 2 hours of
the observer’s meridian. For the best results, the sun should
be above 175 mils in altitude. Unless an elbow telescope
or the card method paragraph 7-14) is used, the sun must
be below 800 roils in altitude.
7-30. APPARENT DISPLACEMENT
a Parallax. The word parallax is defined as “the difference
in altitude of a celestial body as seen from the center of the
earth and from a point on the surface of the earth.” An observed
altitude of the sun is corrected for parallax; that is, for the
error introduced by the fact that the observer is on the surface
of the earth and not at the center. (See Figure 7-41.) This
difference is negligible on vertical angles to the stars because
they are so far from earth. The constant for the parallax of the
sun is considered as +7 seconds, or +0.04 mil.
Figure 7-41. Parallax correction
7-32
b. Refraction. Refraction (Figure 7-42) is the apparent
displacement of the celestial body caused by the bending
of light rays passing through layers of air of varying density.
The refraction varies according to the altitude of the light
source above the horizon. At a temperature of +70°, refraction
of a body on the horizon is 10.26 mils; refraction of a body
at the observer’s zenith is 0 mils. Refraction increases with
an increase in barometric pressure and a decrease in
temperature. It decreases with a decrease in barometric
pressure and an increase in temperature. The refraction
correction is extracted from FM 6-300 (Table 1b) and is
applied to observed altitudes of the sun and stars. The sign
of-the refraction correction is always minus.
Figure 7-42. Refraction correction
FM 6-2
7-31. ALTITUDE METHOD
COMPUTATIONS
a. In solving for azimuth as in other survey problems, a
standard DA form has been designed to facilitate the
necessary computations. DA Form 5594-R (Computation of
Astronomic Azimuth by Altitude Method, Sun (BUCS))
(Figure 7-43) and DA Form 5595-R (Computation of
Astronomic Azimuth by Altitude Method, Star (BUCS))
(Figure 7-44) have been designed to solve for azimuth by
the altitude method formula. (Reproducible copies of both
of these forms are included at the back of this book.)
b. The top portion of the DA forms is set up basically the
same as the other BUCS forms you have used. The top six
blocks are for administrative information. Below the
administrative data, you will find notes that refer to the
operation of the BUCS in this program. Under the notes on
the left side of the form, you will find specific instructions
on the use of this form. To the right of the instructions,
you will find the data record where all known, field, and
computed data are recorded. Blocks that are marked with a
bold arrow are where field data are entered. One complete
observation (three sets) can be recorded and computed on
each form.
c. The procedures for computing
.
-DA Form 5594-R are shown
in Table 7-2.
Table 7-2. Instructions on computing DA Form 5594-R
7-33
FM 6-2
Table 7-2. Instructions on computing Da Form 5594-R (continued)
7-34
FM 6-2
Figure 7-43. Sample DA Form 5594-R
7-35
FM 6-2
d. The procedures for computing DA Form 5595-R are
shown in Table 7-3.
Table 7-3. Instructions on computing DA Form 5595-R
7-36
FM 6-2
Table 7-3. Instructions on computing DA Form 5595-R (continued)
7-37
FM 6-2
Figure 7-44. Sample DA Form 5595-R
7-38
FM 6-2
7-32. FIELDWORK
7-33. EFFECT OF ERRORS
The fieldwork necessary for determining azimuth by the
altitude method includes measuring the horizontal and
vertical angles and recording the time of the observation
and the temperature. The temperature should be recorded
at the beginning of the observation and again when the
observation has been completed. The mean temperature
is used in the computation. The watch used in the
observation should be checked with radio time signals
to determine the watch correction. The time signals for
the Western Hemisphere are broadcast by radio station
WWV at Fort Collins, Colorado, at frequencies 2.5, 5,
10, 15, 20, and 25 megahertz (MHz). Signals for the
Eastern Hemisphere, broadcast by station JJY at Koganei,
Japan, can be received at frequencies of 2.5, 5, 10, or 15
MHz. Each minute during the day, a tone is sounded
and the exact time of the tone is announced. The voice
announcement begins about 10 seconds before the time
signal with the words “At the tone, the time will be (time),
universal coordinated time.” This announcement is
followed by the sounding of the tone. The time announced
is universal time. Set the minute hand of the watch to
be used exactly to the time signal. Make no attempt to
set the second hand. Determine the watch correction by
noting the position of the second hand at the time of
the tone. Then record as the watch correction the number
of seconds at which the second hand was positioned before
or after the 0 second mark, along with the proper sign.
The procedure for time signals elsewhere may vary slightly
from those given above.
Particular attenlion should be paid to secure the best
available data. Roughly, an error of 1 minute in latitude,
declination, or altitude may cause a corresponding error
of more than 0.5 mil in azimuth. Time is less important
in a sun observation because an error of 5 minutes cannot
change the azimuth more than 0.03 mil. For star
observation, only the date is required.
7-34. DETERMINATION OF FINAL
AZIMUTH
a. Technique for Determining Azimuth for Fifth-Order
Survey. To determine azimuth for a fifth-order survey
by using the T16 theodolite, observe and compute at
least three sets of observations (each set, one position).
Mean the azimuths, and reject any set that varies from
the mean by more than 0.3 mil. At least two sets must
be meaned to determine final azimuth.
b. Technique f o r Determining Azimuth for
Fourth-Order Survey. To determine azimuth for a
fourth-order survey by using the T2 theodolite, observe
and compute at least three sets of observations (each
set, one position). Mean the three azimuths, and reject
any set that varies from the mean by more than 0.150
mil. At least two sets must be meaned to determine the
final azimuth.
Section VI
ARTY ASTRO OBSERVATION METHOD (SUN)
In the arty astro method of determining azimuth, two sides of the PZS triangle (Figure 7-21),
the polar distance and colatitude, and one angle are used to solve for the azimuth angle. This
computation is based on the time of the observation. The problem of determining azimuth
consists of taking a horizontal reading at the observer’s station between the mark and sun,
the azimuth of which can be computed. The simple operation of subtracting this horizontal
angle from the computed azimuth of the sun gives the desired azimuth to the mark.
7-35. POSITION OF SUN
For observations by the arty astro method, the sun must
not be wilhin 1 hour of the observer’s meridian. For best
results, the sun should be above 175 mils in ahitude. Unless
an elbow telescope or the card method is used, the sun
must be below 800 mils in altitude.
7-36. ARTY ASTRO (SUN/STAR)
COMPUTATIONS
a. Arty astro is computed on DA Form 7285-R
(Computation of Arty Astro (Sun/Star) (BUCS) (Figure
7-45). This form is basically the same as other forms used
for computations with the BUCS. The administrative data
7-39
FM 6-2
are recorded on the bottom instead of on the top of the
page. The left side of the form show the instructions for
use of the form, and the right side shows the data record
where all field work, known data, and computed data are
recorded. One complete observation can be recorded and
computed on this form.
b. The instructions for computing DA Form 7285-R are
shown in Table 74. Program 13 uses the “electronic
ephemeris,” which allows the obsemation to be computed
by using the internal time module of the BUCS to determine
the date and time for each obsavation. However, the date
and time can be entered manually. If the internal clock is
used, each set has to be computed before the next reading
can be made.
Table 7-4. Instructions for computing DA Form 7285-R
7-40
FM 6-2
Table 7-4. Instructions for computing DA Form 7285-R
7-41
FM 6-2
Figure 7-45. Sample DA Form 7285-R
7-42
FM 6-2
Figure 7-46. Reverse of DA Form 7285-R
7-43
FM 6-2
Section Vll
ARTY ASTRO METHOD (STAR)
The arty astro method can be used with observations on Polaris or on east-west stars. Used with
Polaris, this method yields the most accumte azimuths. When the arty astro method is used with
east-west stars, the requirement for accurate time is a disadvantage, but the method can be used
when no stars meet the position requirements for the altitude method. Computation of arty astro
star is the same as the computations for arty astro sun. The only differences are steps 9 and 9a of
the form. Step 9 will be amwered N (no). Step 9a asks for the star number which can be found
on the reverse of the computation form.
7-37. POSITION OF STARS
The star chart is used for selecting east-west stars for arty
astro observations. Polaris should be observed anytime it is
visible. Best results are obtained when it is above 175 mils
in altitude to minimize the effects of refraction.
7-38. OBSERVATION AND
IDENTIFICATION OF POIARIS
When Polaris is moving fmm eastern to weatem elongadou
its altitude is greater than the latitude of the observer. When
Polaxis is moving tlom weatem to eastern elongatio~ its
alitude is less than the latitude of the obsewer.
c When the telescqe is diwted at Polaris, the observer
will see two other stars nearby that are not visible to the
naked eye. However, Polaris will be the only star visible
when the cross hairs are lighted.
a Polaxis appeam to move in a small, elliptical,
counterclockwise orbit about the celestial North Pole.
Because Polaris stays so close to the celestial North Pole,
it is visible throughout the night in most of the Northern
Hemisphem. When the Polaris local hour angle is 0 or 12
hours, the star is said to be in its upper or lower culmination,
respectively. (See Figure 7-47.) When the Polaris local hour
angle is 6 or 18 hours, the star is said to be in its western
or eastern elongation, respectively. The small orbit of Polaris
results in a very slow apparent motion, so the star can be
observed at any point in its orbit. The least chance of error
in tracking, however, will occur when the star is in elongation.
b. To help identify Polaris, set the latitude of the observer’s
position as a vertical angle on the observing instrument and
point the telescope north. The line of sight will be near the
celestial North Pole, and since Polaris is very near the pole,
the star should appear in the field of view. If the star is in
elongation, its altitude will equal the obsewer’s latitude.
Figure 7-47. Orbit of Polaris
Section Vlll
POLARIS TABULAR METHOD
The computational methods discussed in Sections V, VI, and VII are satisfactory for both fourth-order
and fifth-order work. The Polaris tabular method of computation will achieve reliable fourth- and
fifth-order accuracies. The Polaris tabular method uses the azimuths to Polaris that are tabulated
in FM 6-300, Table 12. These azimuths are corrected by factors related to the observer’s latitude
and the date and time of observation.
7-44
FM 6-2
7-40. DA FORM 5598-R
administrative data you will find notes that refer to the
operation of the BUCS in this program. Under the notes on
the left side of the form, you wilt find specific instructions
on the use of this form. To the right of the instructions,
you will find the data remd where all known, field, and
computed data are recorded. Blocks that are marked with a
bold arrow are where field data are entered. One complete
obsewation can be remrded and computed on each form
(three sets).
a. The top portion of DA Form 5598-R is set up basically
the same as the other BUCS forms you have used. The top
six blocks are for administrative informstion. Below the
b. The instructions for computing DA Form 5598-R are
shown in Table 7-5.
7-39. COMPUTATION OF AZIMUTH
DA Form 5598-R (Computation of Astronomic Azimuth
by Polaris Tabular Method (BUCS)) (Figure 7-48) is used
to compute astronomic azimuth by the Polaris tabular
method with a BUCS. (A reproducible copy of this form
is included at the back of this book.)
Table 7-5. Instructions on computing DA Form 5598-R
7-45
FM 6-2
Table 7-5. Instructions on computing DA Form 5596-R (continued)
7-46
FM 6-2
Figure 7-48. Sample DA Form 5598-R
7-47
FM 6-2
Section IX
SIMULTANEOUS OBSERVATIONS
Simultaneous observations of a celestial body provide a quick method of transmitting direction
over great distances without time-consuming computations. This method is ideally suited to the
needs of the artillery since many units ean be placed on common directional control in a very
short period of time. Because of the great distance of celestial bodies from the earth, the azimuths
to a celestial body at any instant from two or more close points on the earth are approximately
parallel. The difference in the azimuth is caused by the fhct that the azimuths at different points
are measured with reapcet to different horizontal planes.
7-41. PROCEDURES
FOR SIMULTANEOUS
OBSERVATIONS
a. Flank stations are established at points where azimuth is
required. A master station is established at a point from
which the grid azimuth to an azimuth mark is known or
has been computed. (See Figure 7-49.) (An assumed azimuth
may be used.) Both the flank and master stations should be
points that are easily identified on a map and provide the
best possible communications.
b. An observing instrument is set up at the master station
and oriented on the azimuth mark. An observing instrument
is set up at eaeh flank station and oriented on a reference
mark to which the azimuth is required. (See Figure 7-50.)
The observing instrument at the master station must be of
equal order as, or higher order than the instrument used at
the flank station. A prominent celestial body is seleeted by
the obsemerat the master station and identified to the observer
at each flank station. On command, an assistant will key
the microphone so the observer can transmit information at
the same time he observes a celestial body. A headset;
loudspeaker, orotherdevice must be provided for the observer
at each flank station so he ean hear instructions from the
obsewer at the master station. When all stations are ready
to obseme, the master station obsemer announces READY,
START TRACKING (countdown), TIP. Each flank station
observer, when observing a star, places the vertical cross
hair of his instrument on the star and keeps it there by using
the horizontal recording motion tangent screw. When
observing the sun, he centers the sun inside the solar circle.
He keeps it centered by using the tangent screws. The master
station observer announces TIP at the instant the star is at
the intersection of the cross hairs or when the sun is centered
in the solar circle. The observer at the master station records
the readings on the horizontal and vertical scales. Each flank
station observer records the reading on the horizontal scales.
7-48
All observers then plunge their telescopes and repeat the
tracking procedure.
Figure 7-49. Simuitaneous observations
FM 6-2
c. At the master station, the measured horizontal angle is
added to the known azimuth to the mark to determine the
azimuth to the sun. The grid coordinates of the master station,
the vertical angle to the sun, and the grid azimuth of the
sun are transmitted to each flank station. The flank station
operator plots on his map a line representing the azimuth
from the master station to the celestial body. From the flank
station, a line is drawn perpendicular to the line representing
the azimuth from the master station to the celestiat body.
(See Figure 7-50.) The flank station observer then determines
the correction to be applied to the azimuth from the master
station to the celestial body. When this correction is applied
(added or subtracted), the result is the azimuth from the
flank station to the celestial body, The correction is
determined by using the correction nomograph in Figure
7-51 (or Table 13 of FM 6-300).
Figure 7-50. Relative Iocations of stations for simultaneous observations
7-49
FM 6-2
Figure 7-51. Correction nomograph
7-50
FM 6-2
d. The nomograph consists of three columns. The left column
is graduated in meters from 100 to 1,000. It represents the
value of the length of the line (D) from the flank station to
the plotted line that represents the azimuth to the sun from
the master station. The center column is graduated in seconds
and roils from 0.5” to 70” and from 0.003 mil to 0.34 mil
and is the correction (C). The right column is graduated in
degrees and roils from 10” to 65° and from 180 roils to
1,150 mils. It represents the vertical angle to the celestial
body at the master station (H). Before C can be determind,
the values of D and H must be known and used as arguments
in the nomograph. When the distance exceeds 1,000 meters,
it must be divided by 10, 100, or 1,000 to obtain a value
between 100 and 1,000. In such cases, the chart value of
C must be multiplied by the same value by which the distance
was divided. The value H must be between 180 and 1,150
mils. If the flank station is to the left of the line from the
master station to the celestial body, the sign of the correction
is plus; if the flank station is to the right the sign of the
correction is minus.
e. When the azimuth to the sun from the flank station has
been determined, the measured horizontal angle is subtracted.
The result is the azimuth to the azimuth mark at the flank
station.
7-42. ACCURACY OF SIMULTANEOUS
OBSERVATIONS
a. Simultaneous observations are comparable in accuracy
to an astro observation with a theodolite or aiming circle.
The accuracy cannot exceed that of the instrument used.
Requirements for the various accuracies are discussed below.
(1) Requirements for fourth-order azimuth (±0.150 mil)
are as follows:
• A known azimuth of fourth-order or better and a
T2 theodolite at the master station.
Ž A T2 theodolite at the flank station.
7-51
FM 6-2
(2) Requirements for fifth-order azimuth (+0.3 mil) areas
follows:
• An azimuth of fifth-order or better and a T16 or
T2 theodolite at the master station.
• T16 at the flank station.
(3) Requirements for 1:500 azimuth (±0.5 mil) are as
follows:
• An azimuth of fifth-order or better and a T16
theodolite at the master station.
• An aiming circle at the flank station.
(4) Specifications arc the same as for an astro observation
(Appendix B).
(5) Station displacement (cumature) corrections must be
applied (paragraphs 7-41c and d).
b. When a T16 theodolite is used at a flank station and a
T2 theodolite is used at the master station and the conditions
of a above are met, the maximum accuracy that can be
realized will be fifth-order azimuth or ±0.3 mil. If the master
station instrument is a T16 theodolite and the flank station
instrument is an aiming circle, the maximum accuracy to
be expected is ±0.5 mil.
Note. Simultaneous observations will yield the same
accuracy as astro azimuths taken with the
instructions used to a maximum D value of
approximately 26,000 meters. Obseservations may be
conducted over much Ionger distances if a 1-roll or
2-roll accuracy is acceptable.
7-43. HASTY ASTRO OBSERVATION
a. This method enables battalion surveyoxs and firing battery
personnel to compute a grid azimuth and a check angle
from observations of the sun or a selected survey star. The
accuracy of the computation depends on which instrument
is used to perform the observations (M2A2 aiming circle
±2.0 mils or T16 theodolite ±0.3 mils).
b. The fieldwork for this method is the same as the fieldwork
for a flank station simultaneous observation. The hasty astro
program is the master station for the observation. A T2 does
not have a nonrecording motion; therefore, it will not be
used in conjunction with this method.
c. Follow the field procedures below when using a T16
and the hasty astro program. Check angles must compare
within 0.3 mil.(Figure 7-52 shows a hasty astro field sketch.)
(1) Emplace the T16 over the orienting station.
(2) Place 0000.0 mils on the horizontal scale. Lock the
scale with the horizontal clamp.
(3) Track the celestial body (with scale lccked), and
announce TRACKING when the instrument is oriented on
the sun or selected survey star. Announce TIP when the
center of the reticle is exactly aligned on the sun or star.
(4) At the announcement of TIP when using the internal
timer, press the END LINE key on the BUCS. If the internal
timer is not being used, manually enter the date and time
of tip into the BUCS.
(5) When the grid azimuth to the celestial body at the
time of tip is displayed, record this as the azimuth to the
EOL.
(6) Depress the telescope, and emplace the EOL.
(7) Unlock the scales, and repeat steps 3 and 4. The
BUCS will display the check angle. timpme the check angle
from the BUCS to the check angle on the instrument. If the
difference is ±2.0mils for the aiming circle and ±0.3 mil
for the T16 theodolite, the azimuth to the EOL is good; if
not, check all data and/or reobserve.
Figure 7-52. Hasty astro field sketch
7-52
FM 6-2
d. Azimuth from the hasty astro method is computed with
BUCS by using DA Form 72WR (Computation of Hasty
Astro (BUG)) (Figures 7-53 and 7-54) and Program 6.
(A reproducible copy of this form is included at the back
of this book.) This program uses the electronic ephemeris,
which eliminates the need to extract ephemeris data from
FM 6300. This program provides the option of using the
internal timer to determine the date and time of tip for
each observation or to input the date and the time manually.
The ability to manually input the date and time of
observation allows surveyors to perform fieldwork without
the BUCS at the site of observation.
e. The instructions for computing DA Form 721WR are
shown in Table 7-6.
Table 7-6. Instructions to compute DA Form 7286-R
7-53
FM 6-2
Table 7-6. Instructions to compute DA Form 7286-R (continued)
7-54
FM 6-2
Figure 7-53. Sample DA Form 7286-R
7-55
FM 6-2
Figure 7-54. Reverse of DA Form 7286-R
7-56
FM 6-2
Section X
SELECTION OF METHODS OF OBSERVATION
The method selected for observation depends upon the observer's location, celestial bodies available,
and the accuracy required. During daylight hours, only the sun is available. The observer's location
will dictate if the altitude method or the arty astro method must be used. At night, the determining
factors will be the availability and locations of the stars.
7-44. FIFTH-ORDER AZIMUTHS
a. Generally, speed of computation is the most important
consideration in choosing a method for fifth-order astro
azimuth determination. The techniques covered in Sections
V, VI, VII, and VIII are all satisfactory for fifth-order azimuth
determination.
b. At night, in the Northern Hemisphere, Polaris should
always be used if it is observable, because it is easy to
identify and easy to track. When observing Polaris, use
either the arty astro method or the Polaris tabular method.
If Polaris is not visible but an east-west star is, either the
altitude method or the arty astro method can be used. If
the star has a high star rate and accurate time is available,
use the arty astro method. If the star has a low rate, the
altitude method generally is preferable because it requires
less accurate time than does the arty astro method. If time
is not critical and only east-west stars are observable, observe
a star in the east and one in the west.
c. In the daytime, use the sun-altitude method if the sun is
in the proper position, since accurate time is not so important
as it is with the arty astro method. If the sun is not in the
proper position to use the altitude method, use the arty astro
method.
not so critical as it is when used with an east-west body.
The Polaris tabular method will yield reliable fourth-order
azimuths. When Polaris cannot be seen, observe an east-west
star with the arty astro method if accurate time is available.
If time is unreliable, use the altitude method of observation.
c. In the daytime, use the arty astro method with the sun
if accurate time is available; if not, use the altitude method.
7-46. CHOICE OF CELESTIAL BODY
During daylight hours, the sun is the only celestial body
that can be readily observed. At night, Polaris is one of
the most easily identified stars in the Northern Hemisphere.
It is ideal for observation because of its slow movement.
However, Polaris cannot be seen in many parts of the Northern
Hemisphere because of local weather conditions, and it cannot
be used in areas close to the equator and in the Southern
Hemisphere. Therefore, it is inadvisable to depend solely
on this star for night observations. Methods of identification
and approximate locations of the stars on the celestial sphere
in relation to the observer’s position are presented in Section
IV. All artillery surveyors must be familiar with the more
common stars and their relative positions in the sky.
7-47. CHOICE OF METHOD
7-45. FOURTH-ORDER AZIMUTHS
a. Generally, the prime consideration in choosing a method
of fourth-order azimuth determination is accuracy.
Theoretically, the arty astro method is more accurate than
the altitude method, but this accuracy depends in turn on
the availability of accurate time.
b. The beat source of fourth-order accuracy is the Polaris
arty astro method. (Polaris is never observed by the altitude
method.) Polaris is easily identified and tracked, and when
the arty astro method is used with Polaris, accurate time is
The primary considerations in selecting a method of
determining azimuth are as follows:
• The time availabIe to the observer.
• The instruments available for the observer’s use.
Ž The observer's knowledge of the correct time.
• The observer's experience in astro observations.
The secondary consideration is the degree of accuracy desired.
Refer to Table 7-7 for a comparison of azimuth determination
methods.
7-57
FM 8-2
Table 7-7. Comparison of methods for determining azimuth
7-48. SOLUTION OF THE PZS TRIANGLE
TO ESTABLISH AZIMUTH
(SOUTHERN HEMISPHERE)
manner as in the Northern Hemisphere. However, other
techniques must be used in determining the polar distance
and true azimuth.
The Army must be prepared to undertake field operations
at any location on the earth. Hence, the artillery surveyor
must be able to function effectively at any and all locations,
to include those in the Southern Hemisphere.
b. The polar distance is determined by algebraically adding
the declination of the celestial body to 90° (1,600 mils) with
due regard for the algebraic sign of the declination. In the
Southern Hemisphere, the true azimuth to the celestial body
is determined by adding the azimuth angle to or subtracting
it from 3,200 mils. If the celestial body is west of the
observer, the azimuth angle is added to 3,200 mils; if the
body is east of the observer, the azimuth angle is subtracted
from 3,200 mils. (See Figure 7-55.)
a. Locations within the Southern Hemisphere present new
problems to an observer accustomed to working the PZS
triangle in the Northern Hemisphere. The coaltitude
colatitude, and local hour angle are computed in the same
7-58
FM 6-2
Figure 7-55. Comparison of the PZS triangle in the Northern and Southern Hemisphere
7-59
FM 8-2
CHAPTER 8
GYROSCOPIC AZIMUTH
This chapter discusses the skills needed to operate the azimuth gyro
(SIAGL [Lear]). It also discusses the conversion of the azimuth determined
by gyroscope (true azimuth) to grid azimuth.
Section I
SIAGL (LEAR)
This section is a guide for survey personnel to develop the skills needed to operate the azimuth
gyro. The azimuth gyro available for use is the SIAGL (Lear). The SIAGL is a portable gyrocompass
used to determine a true north direction at any selected station, latitude permitting. The SIAGL
can determine direction without lengthy computations or existing control in almost any weather
condition. Accuracy of the SIAGL is comparable to that of astro observation. All persons involved
in FA survey operations must understand the functions of this instrument and be able to determine
a direction with it.
8-1. PRINCIPLE OF OPERATION
A gyroscope acts as a north-indicating device. When leveled,
the gyroscope detects the earth’s rotation and orients itself
to north. Once the gyroscope locks in on north, the true
azimuth to any point can be determined by reading the
horizontal scales. Since the effects of the earth’s rotation
vary from place to place, the gyroscope will be less accurate
at points farther north or south of the equator.
8-2. COMPONENTS AND ACCURACY
a. The SIAGL can determine true north with high accuracy
without the help of celestial or landmark sightings. The
SIAGL consists of the following:
Ž Gyroscopic reference unit (GRU) with an integral
theodolite and tripod assembly.
• Electronic control unit (ECU).
Ž Transit case, which houses the reference unit.
Ž Alternating current-direct current (AC-DC) converter.
• Auxiliary equipment.
The complete SIAGL, minus the wind screen, is contained
in a transport case. The instrument can determine and indicate
true north within about 20 minutes after power is applied.
b. The accuracy of the SIAGL depends on the latitude of
the location. The accuracy at a specific location can be
computed by the formula:
0.150 mil
Accuracy = cosine of latitude
Table 8-1 lists the accuracies that can be expected at various
latitudes from 0° to 75°.
Table 8-1. Azimuth observation accuracy table
8-1
FM 6-2
c. The real value of the SIAGL is to establish initial
directional control for cannon battalion surveys.
d. The LATITUDE select switch on the ECU maintains
instrument operating time at different latitudes of operation.
The switch is adjusted with a screwdriver and has eight
positions. Adjust the LATITUDE switch to correspond to
the closest latitude of operation. Table 8-2 lists the switch
positions and their corresponding latitudes.
Table 8-2. ECU LATITUDE select switch position
e. The TEST METER on the ECU provides a visual check
of the operational status of the instrument in both testing
and operating modes. Satisfactory operation of the circuits
associated with TEST SELECT switch positions is indicated
when the meter pointer moves to the green area (right of
center). The meter and the TEST SELECT switch are used
with the PRESS TO TEST switch, which must be pressed
to obtain meter readings during self-test operations. When
the gyrocompass activates, the meter pointer indicates the
relationship of the pendulum and follow-up assembly.
f. For the specific functions of other GRU controls (Figure
8-1) and ECU controls (Figure 8-2), refer to TM
5-6675-250-10.
8-3. INITIAL SETUP PROCEDURES
The following steps are performed when unloading and
unpacking the equipment.
a. Remove the GRU from the transit case as discussed below.
(1) Press the pressure relief valve.
(2) Unfasten the latches securing the upper and lower
sections of the case together. Remove the upper section.
(3) Unfasten the clamps securing the GRU in the case.
Remove the unit from the case.
(4) Inspect equipment for damage and for loose or
missing parts.
8-2
FM 6-2
CAUTION
Avoid unnecessary exposure of the equipment to
dust, soil, or other abrasive materials.
b. Loosen the clamps on each leg of the tripod, and extend
each leg to within 1/2 inch of full extension. Tighten the
leg clamps. Extend the spades 1/4 to 3/8 inch by rotating
the leveling screws.
Figure 8-1. Gyroscopic reference unit
8-3
FM 6-2
Figure 8-2. Electronic control unit controls
8-4. FINAL SETUP PROCEDURES
With the equipment unpacked and the tripod extended (Figure
8-3), complete setup procedures as discussed below.
a. Course-level the instrument by releasing one of the tripod
leg clamps. Adjust the leg to obtain a level indication on
8-4
the tripod circular level. Repeat the procedure for each of
the other two tripod legs.
b. To center the unit over a fixed reference point, extend
the plumb pointer located on the bottom of the GRU housing.
Place the reference unit on the ground so the pointer is near
the fixed point. Press the leg spades into the ground. Check
the plumb pointer from two positions 1,600 mils apart.
FM 6-2
CAUTION
When ground wind speeds are more than 20 miles
per hour, use of the wind shelter is mandatoryto obtain
azimuth accuracies listed in Table 8-1.
c. Release the horizontal lock on the theodolite. Rotate the
alidade to position the objective end of the telescope over
the NORTH mark on the reference unit; tighten the horizontal
lock. The telescope must be level (white index marks lined
up) for the compass to operate properly. Release the three
hold-down clamps. Depress the plunger on the magnetic
compass. Rotate the GRU in the tripod until the two compass
needle images are in coincidence. Check to ensure the plumb
pointer is still over the fixed reference point. Adjust the
plumb as necessary, tighten the hold-down clamps, and
recheck the compass.
d. Connect the interconnect cable between the ECU and
the GRU. Connect the power cable between the INPUT
POWER connector on the ECU and a 24-volt DC power
source. Auxiliary cables and the AC-DC converter are stored
in the transport ease for use as needed. The AC-DC converter
allows operation from a 115-volt, 60- or 400-Hz power
source. Remove the converter from the transport ease by
unfastening the screw assembly. Cap and chain assemblies
protect the two receptacles on the converter. One receptacle
connects the converter to the power source. The second
receptacle connects the converter to the control unit.
CAUTION
Observe the cable markings and connectors. The
cables may be connected backward if not aligned
properly.
e. For fine leveling, rotate the theodolite alidade so the long
axis of the plate level is in the same plane as any two of
the tripod legs. Adjust the fine level control to place the
bubble in the center of the level vial. Rotate the alidade
1,600 mils, and adjust the remaining leg. Continue the
process until the alidade can be rotated 6,400 mils without
displacing the bubble more than one division.
Figure 8-3. Tripod assembly
8-5
FM 6-2
8-5. HORIZONTAL CIRCLE ALIGNMENT
PROCEDURE
Figure 8-5. Horizontal scale reading
Align the theodolite horizontal circle to the reference mirror
as discussed below.
a. Place the MODE SELECT switch to THEO ILLUM.
b. Adjust the reticle focus to get a sharp, clear image of
the reticle through the telescope eyepiece.
c. Turn the telescope focus counterclockwise until it stops;
then turn it clockwise two turns.
d. Rotate the telescope to place the mirror azimuth (rounded
to the nearest 5 mils) on the horizontal scales.
e. Depress the telescope until the vertical scales read about
2,400 mils. The green cross or a portion thereof will be
visible in the telescope.
f. Adjust the focus to obtain a sharp, clear image, and center
the green cross in the reticle. (See Figure 8-4.)
Figure 8-4. Correct alignment of telescope reticle
with cross
i. If the vernier scale does not appear under the fixed index,
adjust the micrometer control to position the fixed index
mark of the horizontal scale to the center of the nearest
double line.
j. Record the H-scale reading (Figure 8-5) as discussed
below.
(1) If the fixed index is over a three-digit number, record
the number and add a 0 as the fourth digit.
(2) If the fixed index is over a number 5, record the
preceding three-digit number and add a 5 as the fourth digit.
k. Record the vernier scale reading.
l. Obtain the direct horizontal reading by adding the recorded
readings of the horizontal and vernier scales. (See Figure
8-5.)
m. Obtain reverse readings as discussed below.
(1) Release the horizontal and vertical locks on the
telescope, and plunge the telescope.
(2) Subtract 3,200 mils from the mirror azimuth. Place
the first four digits of the answer on the horizontal scales.
(3) Depress the telescope until the vertical scales read
about 4,000 mils.
g. Adjust the microscope focus control and the THEO BRT
control until the scales appear in clear focus.
(4) Repeat steps in h through 1 above to obtain the reverse
mirror reading.
h. Adjust the micrometer control to position the fixed index
mark (Figure 8-5) of the horizontal (H) scale to the exact
center of the nearest double line.
n. Obtain the mean mirror reading as discussed below.
8-6
(1) Apply 3,200 mils to the reverse reading.
FM 6-2
(2) Add the direct and reverse readings.
(3) Divide the sum obtained in (2) above by two to obtain
the mean mirror reading.
o. If the mirror reading determined in n above is within
0.04 mil of the value displayed on the mirror azimuth plate
just below the reference mirror window, make no adjustment.
If the error is greater than 0.04 mil, use the adjustment
procedures below.
(1) Subtract the last four digits of the reverse reading from
the last four digits of the direct reading. (Disregard the first
two digits.)
(2) Divide this value by two to determine the collimation
error.
(3) Algebraically add the collimation error to the value on
the mirror azimuth plate.
(4) With the telescope in the direct position, center the
image (green cross) accurately in the reticle pattern as in a
through f above. Using the micrometer, set the value
determined in (3) above on the horizontal and vernier scales.
Using the horizontal circle adjusting tool, center the index
between the nearest double line. See Figure 8-1 for location
of the horizontal circle setting control.
(5) Take an additional direct and reverse reading.
Compare these with the mirror azimuth plate, and repeat
adjustment until the desired reading is obtained.
8-6. SELF-TEST
Place the telescope in the direct position. Perform the self-test
as discussed below.
a. With the MODE SELECT switch set to SELF TEST and
the PWR ON indicator lit, place the TEST SELECT switch
to SOURCE VOLTAGE.
b. Press the PRESS TO TEST switch. Verify that the TEST
METER pointer falls between 22 and 33 volts DC on the
meter scale.
Note. You must press the PRESS TO TEST switch
for each of the test positions.
c. Place the TEST SELECT switch to REG AC. Verify
that the TEST METER pointer is in the green band of the
meter scale.
that the theodolite rotates in a clockwise direction and the
TEST METER pointer is in the green band of the meter
scale.
f. Place the TEST SELECT switch to the SERVO CCW
position. When looking down on the reference unit, verify
that the theodolite rotates in a counterclockwise direction
and that the TEST METER pointer is in the green band of
the meter scale.
g. Place the TEST SELECT switch to either SERVO CW
or SERVO CCW until the yellow index mark is in the center
of the yellow servo operating band.
h. Place the TEST SELECT switch to BRAKE. Verify
that the BRAKE ON indicator lights and the TEST METER
pointer is in the green band.
i. Place the TEST SELECT switch to GYRO. Verify that
the TEST METER pointer centers in the yellow area of the
test meter scale (0).
8-7. OPERATION OF THE
INSTRUMENTS
Note. For daytime operation, the PANEL ILLUM
control must be in the DAY position and the theodolite
illumination must be at least two-thirds full illumination.
a. Place the ECU MODE SELECT switch to BIAS (audible
click).
b. Rotate the CAGE-UNCAGE knob on the GRU clockwise
until the UNCAGED indicator lights (audible click). If the
GRU will not uncage, check the fine level of the instrument.
c. Observe the TEST METER pointer swing left and right
at an approximate rate of one reversal every 5 seconds. When
the pointer comes to a stop, verify that it is at 0. If necessary,
unlock the outer ring on the BIAS control by turning it
counterclockwise, and turn the inner control knob in the
appropriate direction to move the needle to 0. When the
pointer is at 0, turn the outer ring clockwise to lock the
BIAS control in position.
d. Rotate the CAGE-UNCAGE knob on the GRU
counterclockwise until the UNCAGED indicator goes out
(audible click).
d. Repeat step c with the TEST SELECT switch in the
REG DC and BIAS positions.
e. Place the MODE SELECT switch to GC (gyrocompass).
Verify that the GYRO SYNC indicator lights within 2
minutes.
e. Place the TEST SELECT switch to the SERVO CW
position. When looking down on the reference unit, verify
f. Rotate the CAGE-UNCAGE knob clockwise until the
UNCAGED indicator lights.
8-7
FM 8-2
CAUTION
During the initial wait for the READ AZIMUTH light,
ensure the yellow index mark does not approach
either end of the yellow servo operating band. Failure
to keep the index mark near the center of the operating
band will cause extensive damage to the instrument.
If the yellow index mark does approach either end of
the servo operating band, place the CAGE-UNCAGE
knob in the CAGE position. Rotate the GRU in the
tripod 60° in the direction that the index mark was
moving. Relevel and rebias the instrument, then
proceed with the gyrocompass operation.
g. Verify the READ AZIMUTH indicator on the ECU lights
about 15 minutes after uncaging the gyro.
h. After the READ AZIMUTH indicator light illuminate,
take a direct and reverse reading on the azimuth mark with
the theodolite and record the readings. This constitutes one
set of readings. With the telescope in the direct position,
press the RESET button. The READ AZIMUTH indicator
light will illuminate in about 45 seconds. Take a second
set of readings to the azimuth mark. The mean of each set
must agree within 0.3 mil for fifth-order accuracy. If time
permits, take another set of readings to check the mean of
the first two sets.
f. Adjust the microscope focus control and the optical scales
THEO ILLUM control on the ECU panel until the H-scale
image appears in clear focus.
g. Adjust the micrometer to position the fixed index mark
of the H-scale to the center of the nearest double line.
h. If the vernier scale does not appear under the fixed index,
adjust the micrometer to position the fixed index mark of
the H-scale to the center of the nearest double line.
i. Record the H-scale reading (Figure 8-5) as discussed
below.
(1) If the fixed index is over the three-digit number, record
the number and add a O.
(2) If the fixed index is over a number 5, record the
preceding three-digit number and add a 5.
j. Obtain the direct azimuth indication by adding the recorded
readings of the horizontal and vernier scales.
k. Read the vertical scales (Figure 8-6) in the same manner
as the horizontal scales.
Figure 8-6. Vertical scale reading
i. Stop the gyroscope by the procedures outlined in
paragraphs 8-9a(2) and (3).
j. Place the MODE SELECT switch to BIAS. Rotate the
CAGE-UNCAGE knob on the GRU clockwise until the
UNCAGED indicator light illuminates. Recheck BIAS to
ensure that the TEST METER pointer is within the shaded
(yellow) band of the meter.
k. If the difference between the two meaned azimuths is
greater than 0.3 mil or if the TEST METER pointer is not
within the shaded (yellow) band, disregard the two sets of
readings. Retake both sets, starting with c above.
8-8. READING THE THEODOLITE
a. Adjust the reticle focus to obtain a sharp, clear image
of the reticle seen through the telescope eyepiece.
b. Release the horizontal and vertical locks on the theodolite.
c. Align the telescope on the target, and tighten the horizontal
and vertical locks.
l. Mathematically average the last four digits of the direct
and reverse readings to determine true azimuth (recorded
as shown in Figure 4-15).
m. Convert the true azimuth to grid azimuth by using the
BUCS. (Refer to Chapter 8, Section II.
8-9. MARCH-ORDERING EQUIPMENT
d. Adjust the telescope focus until the target appears in clear
focus.
a. Take down the instrument as discussed be!ow.
e. Adjust the azimuth and elevation controls to center the
target image accurately in the reticle pattern.
(1) Rotate the CAGE-UNCAGE knob counterclockwise
until the UNCAGED indicator light is out.
8-8
FM 6-2
(2) Place the MODE SELECT switch to BRAKE ON.
Verify that the BRAKE ON indicator lights and goes out
at the completion of the braking sequence (in about 90
seconds).
(3) Place the MODE SELECT switch to PWR OFF.
(4) Verify that the yellow index mark is in the center
of the yellow operating band. If it is not, place the MODE
SELECT switch to SELF TEST. Place the TEST SELECT
switch to BIAS CW or CCW to center the index mark.
Then place the TEST SELECT switch to BRAKE, and return
the MODE SELECT switch to PWR OFF.
Note. Center the Index mark in the yellow operating
band to be sure the GRU will fit in the transit case.
(5) Dismantle the equipment in reverse order of setup
for removal from service or transport to a new work site.
b. Secure the transit case by fastening the upper and lower
sections of the case together. Place the transit case in the
transport case, and fasten the strap latches.
c. When using vehicle transportation, securely tie the
transport case down before moving.
8-10. MAINTENANCE
The SIAGL will operate in all climatic categories. However,
because of known design limitations of theodolites, use of
the procedures below will permit successful operation.
a. Avoid subjecting the instrument to extreme sudden
changes in temperature.
b. Allow the instrument to stabilize at the operating
temperature.
c. Select operating sites that can shield or protect the
instrument from the full effects of the extreme environment.
Make use of available tents or other shelters.
d. At the end of a mission, return the instrument to its
transport case. Do not allow the instrument to be exposed
in conditions where it cannot be used.
e. Remove moisture and fogging of the optics by storing
the instrument in a warm, dry place. (Locally fabricated
“hot boxes” and a desiccant can be used.)
f. Adhere to the standard operation, transportation,
maintenance, and storage procedures prescribed for the
various climatic regions.
g. During operations in winds exceeding 20 miles per hour,
use a wind shelter.
h. Ensure that the equipment is clean and dry before storage.
8-9
FM 6-2
Section II
CONVERSION OF GYROSCOPIC AZIMUTH TO GRID
AZIMUTH
The azimuth determined by gyroscope is a true azimuth. For use in artillery survey, this azimuth
must be converted to grid azimuth. The difference between true azimuth and grid azimuth (Figure
8-7) is called grid convergence.
Figure 8-7. Relation of true azimuth to grid azimuth
8-11. DETERMINATION OF
CONVERGENCE
a. The sign of grid convergence correction is plus when
the observer’s station is west of the central meridian and
minus when the station is east of the central meridian. (See
Figure 8-8.) Grid azimuth is determined by algebraically
adding the true azimuth and the value of grid convergence.
If the azimuth is determined in the Southern Hemisphere,
the signs of convergence are opposite the corrections for
the Northern Hemisphere.
b. Convergence is a function of both latitude and longitude.
Its value is computed on DA Form 5599-R
(Computation—Convergence of True Azimuth to Grid
8-10
Figure 8-8. Convergence
Azimuth (BUCS)) (Figure 8-9) by using the geographic
coordinates and the grid zone of the observer. (A reproducible
copy of this form is included at the back of this book.)
This form is basically the same as the other forms that you
have used. The top six blocks are for administrative
information. Below the administrative data, you will find
notes that refer to the operation of the BUCS in this program.
Under the notes on the left side of the form, you will find
specific instructions on the use of this form. To the right
of the instructions, you will find the data record where all
known, field, and computed data are recorded. Blocks that
are marked with a bold arrow are where field data are entered.
Four separate computations for convergence can be computed
on one form. (See Table 8-3 for instructions on computing
DA Form 5599-R.)
FM 6-2
Table 8-3. Instructions for computing DA Form 5599-R
STEP
INSTRUCTION
1
There is no prompt. The procedure in the PROCEDURE column is CALL PROGRAM 9. Enter the survey module,
and call Program 9.
2
The display prompts GRID CONVERGENCE. There is no procedure. Press the END LINE key
3
The display prompts LAT(-:S) 0.0000000. The procedure is ENTER LATITUDE OF STATION. Enter the value of
the latitude. If the latitude is in the Southern Hemisphere, enter it as a negative. Enter the value in the format
DD.MMSS. Record the latitude In the LATITUDE block in the top DATA RECORD section.
4
The display prompts LG(-:W) 0.0000000. The procedure is ENTER LONGITUDE OF STATON. Enter the value of
the longitude. If the observer is in the Western Hemisphere, enter the value as a negative. Enter the value in the
format DD.MMSS. Record the longitude in the LONGITUDE: block in the top DATA RECORD section.
5
The display prompts TRUE AZ: 0.000. The procedure is ENTER TRUE AZIMUTH. Enter the azimuth that is to be
converted to a grid azimuth. Record the azimuth in the TRUE AZIMUTH (MILS): block in the top DATA RECORD
section.
6
The display prompts GRID ZONE: 00. The procedure is ENTER GRID ZONE NUMBER. Enter the grid zone. This
information can be taken from a map of the area. Record the grid zone In the GRID ZONE: block in the top DATA
RECORD section
7
The display prompts CONVG: 0.000. The procedure is RECORD CONVERGENCE. This is the difference
between true and grid azimuth for the location. Record It in the CONVERGENCE (MILS): block in the top DATA
RECORD section.
8
The display prompts GRID AZ: 0.000. The procedure is RECORD GRID AZIMUTH. This is the value of the true
azimuth with the amount of the grid convergence applied. Record it In the GRID AZIMUTH (MILS): block in the top
DATA RECORD section.
9
The display prompts ANOTHER CVG (Y/N): The procedure is ENTER Y OR N. If this step is answered Y (yes), the
program returns to step 2. If this step is answered N (no), the program goes on to step 10.
10
The display prompts END OF MSN (Y/N). The procedure is ENTER Y OR N. If this step is answered N, the
program returns to step 9. If this step is answered Y, the program will return to SURVEY PGM MENU REV1.
8-11
FM 6-2
Figure 8-9. Sample DA Form 5599-R
8-12
C1, FM 6-2
value of the northing coordinate on the center (slanted)
column.
8-12. DETERMINATION OF
CONVERGENCE WITH
NOMOGRAPH
a. Table 6a of FM 6-300 is a grid convergence nomograph.
This nomograph permits a graphic determination of grid
convergence in mils. The arguments for entering the
nomograph are the casting coordinate rounded to the nearest
100 meters and the northing coordinate rounded to the nearest
10,000 meters.
b. The convergence is extracted from the right column of
the nomograph as discussed below.
(1) With a straightedge, align the value of the casting
coordinate on the left column of the nomograph with the
(2) Read the amount of the convergence in roils from
the right column.
(3) Apply the grid convergence to the true, or astronomic,
azimuth to determine the UTM grid azimuth.
c. Grid azimuths determined with the nomograph are
satisfactory for cannon battery orienting lines obtained by
astro observation or gyroscopic means. The nomograph
should not be used to determine convergence when directional
control is initiated at a battalion SCP for fifth-order survey.
*Section Ill
North-Seeking Gyroscope
The north-seeking gyroscope (NSG) is a portable gyro compass that determines both true and grid
azimuth with an accuracy of ±0.2 mil probable error (PE). (See Figure 8-10 on page 8-14.) The
FA surveyor can use the NSG to determine an azimuth, whenever required, that is within artillery
orientation specifications. The NSG does not require any precise orientation or computations.
Detailed information on the operation and maintenance of the NSG and additional equipment can
be found in TM 5-6675-333-10 (TO 33D7-9-53-1).
8-13. PRINCIPLE OF OPERATION
The NSG is a precise survey instrument that finds the direction
of geodetic north and determines azimuths relative to geodetic
north (true north) or grid north. Trained personnel can
determine a grid azimuth (after setup) in about 4 minutes.
During the setup, there is a requirement to enter UTM
coordinates accurate to the nearest 200 meters casting and
1,000 meters northing.
8-14. COMPONENTS
The NSG is housed in three watertight transport cases. Upon
receipt of equipment, inspect each component, including the
transport cases, for completeness and damage in accordance
with (IAW) TM 5-6675-333-10. The instrument can be
transported by vehicle, hand carried by using the carrying
handles, or backpacked by using the shoulder straps located
in each case.
a. SKK3-1 Gyro Compass. The gyro compass is a single
box unit that is designed to fit into the gyro tripod. The
heart of the gyro compass is a gyro motor suspended on a
thin metal tape. Internally the gyro makes two coarse
measurements and one (or two) fine measurements near north
to determine an azimuth. The keyboard is attached to the
gyro compass, and it is the operator’s link to the gyrocompass.
It has alphanumerical screens for data entry and display of
azimuth and system status. The theodolite horizontal scale
can be aligned with respect to the gyro mirror that is viewed
through the autocollimation attachment. Power is applied
to the NSG via the back of the gyro compass.
b. Power Supply.
(1) The SEB42-1 battery is a rechargeable 24-volt
NICAD cell battery that is capable of about 35 measurements
at 68° F. Use of lighting accessories will decrease battery
life. The battery clamps to the rear of the gyro compass
and is protected from discharging by a fuse.
(2) The SLG6-1 battery charger is capable of charging
two SEB42- 1 batteries at the same time, using either AC
or DC. Depending on cell voltage and temperature, the
charger automatically provides the appropriate current. The
charger will accept 10 to 33 v DC or 115 to 230 v AC.
At temperatures between 41°F to 122°F, it takes less than
7 hours to completely charge a dead battery, whereas at
14° F, it may take up to 14 hours.
(3) The SEV22-1 power adapter enables the gyro
compass to be powered directly from vehicle power (9 v to
33 v). The adapter is protected with a fuse and is connected
to the rear of the gyro compass as is the battery.
8-13
C1, FM 6-2
Figure 8-10. North-seeking gyroscope
8-14
C1, FM 6-2
c. T16SK-1 Theodolite. The theodolite is a modified
One
version of the current T16-84 (upright image).
distinction is the autocollimation box attached to the side,
This is used to align the theodolite with the gyro. The
scales are read the same as the T 16-84 scales. The T16SK- 1
comes with accessories such as electric lighting for night
operations, target rod (barber pole with tricolor lights),
eyepiece filter (sun filter), sun shade, adjustment tools, and
rain and dust cover. For a complete list of accessories, see
TM 5-6675-333-10.
Note. The telescope must be in the reverse position
when determining azimuth. The laser range finder
studs will face up when in the reverse position. When
no range finder studs are present, the microscope
(reading scale) will be on the left side of the telescope
when facing the keyboard.
d. GST90-5 Gyro Tripod. The gyro tripod has three
leveling screws, a circular level, a clamping screw, and a
tilting dish capable of lateral movement of 1 inch for simple
positioning of the north-seeking gyroscope. For transport,
there is a protective cover for the tilting dish.
wants to enter location in geographic coordinates, he selects
LC (latitude and meridian correction) from the Control Menu.
(2) Measurement mode. The measurement mode most
commonly used will be 1U. The advantage in using the
1U mode is that the operator does not have to decide whether
or not to calibrate and does not have to know the
zero-calibration procedure.
b. Entering Data. The keyboard is a right fill enter (input)
type of keyboard. This means that when data are entered,
the last number in a string of numbers is entered first. The
decimal point on the keyboard applies only to azimuths.
c. Entering UTM Coordinates. Only four digits are
entered when entering UTM casting and northing during
the setup. When entering the easting coordinate of 546321.5
(accurate to the nearest 200 meters), the user enters 5463
(546,300 meters) by first entering 3, then 6, then 4, and
finally 5. When entering the northing coordinate of
3819765.7 (accurate to the nearest 1,000 meters), enter 3820
(3,820,000 meters) by first entering 0, then 2, then 8, and
then 3.
Note. When surveying within 1,000,000 meters north
of the equator, the user enters three digits northing
and four digits casting.
8-15. INITIAL SETUP PROCEDURES
The NSG can be set up over an established point (point
already in the ground), or a point can be established after
setup. Because of the size and the lack of an easy method
for plumbing the tripod, it maybe easier and faster to establish
the point under the plumb bob after first setting up and
leveling the NSG. If the point is already established, care
must be taken to ensure the instrument is plumbed directly
over the point. Setup procedures are in TM 5-6675-333-10.
Note. In a windy environment, setup the NSG as low
to the ground as possible. The tripod Iegs should be
extended only enough to allow or leveling
procedures.
8-16. SURVEY APPLICATIONS
a. System Settings. When the gyro is turned on, the system
will default to the factory settings of Grid (azimuth), NE
(UTM coordinates), and 1U (standard measurement mode,
which includes self-calibration). To change the azimuth
setting, press the MODE key to select GEO (true north)
and then press the STEP key. There are two other major
settings: local parameters and measurement modes.
(1) Local parameter.
The local parameter most
commonly used will be NE (UTM coordinates). If the user
8-17. DETERMINATION OF
E-2 ADDITIVE CONSTANT
The E-2 additive constant is a setting that can be input into
the gyro computer to compensate for wear and tear on the
instrument. When the equipment is new, the factory setting
is 0 mils. Over time, the connections that fit the theodolite
to the gyro can become worn. This can be caused by rough
use of the equipment or just general wear and tear. For
this reason, the gyro and theodolite must remain as a set,
If for some reason a different theodolite or gyro is used
together, a new E-2 additive constant for the pair should be
determined. This procedure is performed under the following
conditions:
Upon initial receipt of equipment.
When azimuth is suspect.
After rough handling.
Annually.
Upon return from maintenance.
Note. The E-2 constant should be done more often,
at least semiannually, if the gyro gets a lot of use.
8-15
C1, FM 6-2
a. Accuracy. To determine the E-2 additive constant, you
need at least one survey line with an azimuth known to
fourth-order or higher specifications. Ideally, the length of
the survey line should be at least 1,000 meters.
CAUTION
PADS does not meet the requirements to establish
an azimuth line for this procedure. Determining the
E-2 additive constant is a very critical procedure. This
will affect all future azimuths. This procedure should
be performed under the direct supervision of the
survey chief.
b. Procedure for Determining E-2 Additive Constant.
EXAMPLE
Known
Azimuth
Measure Azimuth
E-2new -0.1
Azimuth Corrections E-2old +0.4
+0.3
3200.0
3200.2
= -0.2
3200.2
= -0.2 (-.4)
3199.9
= +0.1 (-.3)
3200.0
=
0.0 (-.3)
3200.2
=
-0.2 (-.5)
3200.1
= -0.1 (-.6)
Mean = -0.6/6= E-2new (-.1)
(1) Set up the instrument at one end of the survey line.
(2) Adjust horizontal collimation error to zero. This
should be done whenever the NSG is being used. Any
collimation error will affect the accuracy of the azimuth
that is determined.
(3) Determine gyro compass azimuth, and orient the
theodolite.
(4) Sight in on the other end of the survey line, and
read the horizontal scales.
(5) Calculate the azimuth correction. This is the additive
constant (E-2). If the measured azimuth is more than the
known azimuth, the correction is a negative value. If the
measured azimuth is less than the known azimuth, the
correction is a positive value. (See the example below.)
Known azimuth
Measured azimuth
Azimuth error
Azimuth correction
c. Procedure for Entering the E-2 Additive Constant.
(1) Press the MODE key until CONTROL appears in
the status display; then press the STEP key.
(2) Use the cursor and +/- key to enter the code (59382).
(3) Press the STEP key to read the previously stored
additive constant.
(4) Compute new additive constant; then algebraically
apply it to the old additive constant as shown above.
(5) Use the cursor and +/- key to enter E-2new, and
press the STEP key to store it.
EXAMPLE
4800.0
1600.0
(6) Record date, old E-2 additive constant, new E-2
additive constant, and horizontal collimation error (if any)
on a label attached to the gyro and protected by some sort
of waterproof material.
4800.2
0.2
-0.2
1599.6
0.4
+0.4
Note. If the azimuth correction appears excessive, the
accuracy of the azimuth line must be verified. Another
option would be to use another verified azimuth line.
(6) Repeat the steps in paragraphs (2) through (5) five
more times (for a total of six corrections).
(7) Algebraically apply the mean (E-2new) additive
constant to the present correction (E-2old). (See the example
below.)
8-16
8-18. MAINTENANCE
Refer to TM 5-6675-333-10 for preventive maintenance
schedule and troubleshooting table.
FM 6-2
CHAPTER 9
POSITION AND AZIMUTH DETERMINING SYSTEM
The PADS is a self-contained inertial surveying system. It can be used
to rapidly and accurately determine position, azimuth, and elevation (PAE)
in either ground or airborne survey operations. It is a precise and sensitive
piece of equipment and should be handled with the same care as any
other precise survey instrument. Detailed information on the PADS
installation, operation, maintenance, and additional equipment is given in
TM 5-6675-308-12.
9-1. SYSTEM USES AND
CONFIGURATIONS
a. System Uses. PADS is used to conduct FA surveys
critical to the fire control function. PADS provides a common
grid for weapon and TA systems. It can determine position,
elevation, and grid or true azimuth for each point surveyed.
b. Configurations. The system (Figure 9-1) can be installed
in and operated from an M151 -series vehicle, a HMMWV,
a commercial utility cargo vehicle (CUCV), and the
small-unit support vehicle (SUSV). These vehicles must have
alternators of 60 amperes or greater. PADS can also be
operated from a UH-1 helicopter and an OH-58 light
observation helicopter. Mounted in the M151-series or
HMMWV, the PADS can also be transported or operated
in a CH-47 cargo helicopter. PADS can be transferred to
UH-60 (Blackhawk) helicopter. (The UH-60 needs a power
converter to convert the helicopter's AC power to DC power.)
Figure 9-1. PADS
9-1
FM 6-2
9-2. PADS COMPONENTS
a. PADS primary pallet contains the basic electronic modules
for the PADS. These are the control and display unit (CDU),
power supply (PS), inertial measurement unit (IMU), and
computer.
(1) The CDU (Figure 9-2) has a keyboard and an
alphanumeric display for data entry and display of survey
data and system commands. The CDU is the input-output
device for the system.
(3) The IMU (Figure 9-4) contains the gyroscopes,
accelerometer sensors, and associated electronics needed to
maintain the survey coordinate frame. It will measure distance
traveled to each coordinate axis.
Figure 9-4. Inertial measurement unit
Figure 9-2. Control and display unit
(2) The PS (Figure 9-3) receives unregulated power from
the transporting vehicle or PADS batteries. It provides
controlled and regulated power to the IMU, computer, and
CDU.
Figure 9-3. Power supply
9-2
(4) The computer (Figure 9-5) Processes IMU data,
computes survey data, and provides system control functions.
The computer accepts data from and sends data to the CDU.
Figure 9-5. PADS computer
C1, FM 6-2
b. The secondary pallet is the battery box. The battery
box (Figure 9-6) contains two 12-volt batteries. They are
used to continue operations while the PADS is transferred
from ground vehicle to helicopter or from helicopter to ground
vehicle. It supplies additional power requirements for
initialization and provides a backup power supply in case
the vehicle power fails. It also houses cables, tools, and
small hardware items.
Figure 9-6. Battery box
9-3. PADS OPERATION
PADS operation requires a two-man party, an assistant PADS
operator (driver-radio operator), and a PADS operator (PADS
party chief). Both must be qualified in FA survey.
a. Preparation for Operation. A PADS mission begins
on receipt of a warning order with before-operation checks
and services, followed by initialization. (See TM
5-6675 -308-12.) After arrival at the initialization point
(which must be within 100 meters horizontal and 10 meters
vertical accuracy), activate the system by switching circuit
breakers 1 and 2 on and pressing the ON-OFF button. Enter
the spheroid, grid zone number, casting and northing
coordinates, and elevation. The PADS then automatically
aligns itself. Initialization takes from 30 to 45 minutes,
depending on ambient temperature. After the PADS has
completed initialization modes 0 through 8 and the CDU
shows a flashing GO light, the system is ready to be updated.
Drive to the SCP, and maneuver the PADS over the SCP
by using the plumb bob suspended from the plumb bob arm
for alignment. Enter the correct grid coordinates and height
of the SCP. PADS is then ready to perform the survey mission.
The SCP may not be accessible to the PADS by using the
plumb bob. In this case, update the system by using a
theodolite. The procedures for updating the PADS by using
a theodolite are discussed in TM 5-6675-308-12, Chapter
3.
b. Zero-Velocity Corrections. Zero-velocity (Z-VEL)
corrections must be performed en route to points to be
surveyed and during the survey mission. The Z-VEL
correction allows the PADS to correct itself to its present
location. Ten minutes is the maximum Z-VEL time allowed.
This is associated with battalion fifth-order survey
requirements. If more accurate survey control is necessary,
a 5-minute Z-VEL correction (associated with div arty or
TAB fourth-order requirements) must be performed. PADS
is automatically set for a 10-minute Z-VEL time. To change
this time, consult TM 5-6675-308-12. The desired Z-VEL
time is entered into the computer after initialization. To
perform a Z-VEL correction, the vehicle must be at a complete
stop and the STOP button on the CDU must be pressed. In
aircraft operations, the aircraft must be stationary on the
ground, but it can continue at flight idle. The PADS requests
a Z-VEL correction be performed by alternately flashing
the GO and STOP indicators and sounding the DS3 ALARM.
This audible alarm will sound 30 seconds before the required
Z-VEL correction.
c. Survey Operations. On arrival at the position to be
surveyed, maneuver the vehicle with PADS over the point
to be established. The PADS operator must know what data
the user requires. He must decide which marking procedure
(plumb bob or theodolite) will be used. If an orienting line
is required in the mission, a two-position azimuth mark-must
be performed. The two-position azimuth mark using the
plumb bob requires that the two points beat least 100 meters
apart and intervisible, The PADS automatically computes
the grid azimuth from the second marked position back to
the first marked position. The coordinates that the PADS
computes are unadjusted. This unadjusted data may be given
to the users with the understanding that the adjusted data
will be given upon completion of the mission. The procedures
for performing a two-position azimuth mark and adjusting
data are also discussed in TM 5-6675-308-12, Chapter 3.
Because of terrain or unit SOP, two-position azimuth marks
may not be the preferred method. In this case, the second
method, marking position, azimuth, and elevation by using
the theodolite, would be used, since there is no distance
requirement.
9-3
C1, FM 6-2
d. Shutdown Procedures. On completion of the survey
mission, the PADS must be shut down. The PADS can be
operated for an unlimited amount of time, but you must
perform an update every 7 hours of operation. If the PADS
is shut down and you are required to do an additional mission
after shutdown, you must wait 2 minutes, then reinitialize.
After initialization is complete, update over a known SCP.
Before shutdown, close out the survey over a known SCP
by updating the system and recalling the adjusted data. The
first step in the shutdown procedure is to conduct a PADS
battery test. This test checks the PADS battery operation
under load. After the battery test, turn off the system. (Detailed
shutdown procedures are listed in TM 5-6675-308-12, Table
3-2.)
9-4. PADS MISSION CLOSURE
a. Field artillery surveyors are accustomed to describing
survey accuracies in terms of survey specifications for
fourth-order (1:3,000) and fifth-order (1:1,000) surveys.
These specifications are described in Appendix B and serve
as rejection criteria for conventional survey techniques.
PADS operations are similar to a conventional traverse. The
computer determines the position of a point by using input
from the accelerometers (compared to measuring the distance
with a tape or distance-measuring equipment). Conventional
traverse errors usually increase during the survey because
of systematic errors in the measurement of angles and
distances. PADS errors also generally increase as the PADS
proceeds along the survey route. However, absolute rejection
criteria cannot be applied to PADS position data. This is
because the error will vary with mission length, duration,
system characteristics, Z-VEL correction periods, and other
factors. In units that require fourth-order conventional
specifications, the PADS uses 5-minute Z-VEL corrections.
In units that require fifth-order conventional specifications,
it uses 10-minute Z-VEL corrections. Acceptability of a
conventional survey is determined by comparing the radial
error of closure with a maximum allowable error in position
and similar criteria for azimuth. PADS performance is
checked by using an update rejection procedure.
b. A PADS survey should be started on fourth-order or higher
conventional survey control or on a PADS SCP established
by using 5-minute Z-VEL corrections. It should be closed
on a second SCP of an equal or higher order survey. If a
second known SCP does not exist, a PADS survey must be
closed on the starting point. If PADS accepts the data, then
the survey is good, if not, refer to TM 5-6675-308-12, Table
3-3.
9-5. UPDATING THE PADS
Entering accurate position and/or elevation data into the
PADS is called updating. Updates should be performed over
9-4
fourth-order or higher conventional survey control. If known
control is not available, update over a PADS SCP established
by using 5-minute Z-VEL corrections, or when no known
PADS SCPs are available, update by using the precise
lightweight GPS receiver (PLGR).
(Refer to TM
5-6675-308-12, Change 3, page 3-36.12). The PADS must
be updated after initialization before it can provide accurate
survey data. The first update after initialization is called
the initial update. The survey mission starts with the initial
update. The PADS must also be updated at the end of a
survey mission. This closing update should be on a second
known SCP. lf a second known SCP does not exist, a PADS
survey can be closed on the starting point, or when no known
SCPs are available, by using the PLGR. As in conventional
survey, if a survey is closed on the starting point (or GPS),
there is no check on the starting control. Care should be
taken to verify these data by using all available means (another
GPS, maps, and so on). The PADS will either accept or
reject the update. If it accepts the update, the PADS
automatically adjusts all data recorded since the previous
update. The adjusted data replace the unadjusted data stored
in the system computer memory. The adjusted data must
be provided to all users.
Note. Position and/or elevation updates can be
performed independently.
a. Update Procedures With Plumb Bob or Theodolite.
Procedures used to update position and/or elevation with
the plumb bob or theodolite are listed in TM 5-6675-308-12,
Table 3-2, steps 3, 4, 5, and 6.
b. Update Acceptance. After the operator has entered the
known trig list positions and/or elevation data of the SCP
into the PADS, the system automatically tests the difference
between the update coordinates (trig list data) and the PADS
position coordinates. If the difference (error) is within the
built-in calibration tolerance parameters, the update is
accepted and the CDU displays ID PAE U-U. This display
tells the PADS operator that the PADS has met the specified
accuracy needed for that update and all surveyed stations
established back to the previous update. When the update
has been accepted by the PADS, the survey is considered
a closed survey within the prescribed accuracy.
c. Update Rejection. If the difference (error) is outside the
built-in calibration tolerance parameters, the PADS recues
for the update data by displaying a flashing E on the CDU,
followed by the data the operator entered. The flashing E
indicates a possible update rejection in position. The operator
then checks the probable reason for the update rejection and
takes the appropriate corrective action as outlined in TM
5-6675-308-12, Table 3-3.
C1, FM 6-2
9-6. PADS SURVEY PLANNING
Because of the speed and accuracy of the system, extensive
planning and a map reconnaissance must be performed. The
mode of travel, route, weather, terrain, and tactical situation
must be considered. Because of time and distance limitations,
SCPs nearest the area of the PADS mission must be used
for starting control. For detailed information on PADS
planning and use of the PADS in FA units, refer to Chapters
14 and 15.
9-7. PADS USE IN SPECIAL
SITUATIONS
The following are special situations in which the PADS can
be used. No additional personnel or equipment is required.
a. Establish a Declination Station. When the PADS is
used to establish a declination station, the criteria for the
predetermined site is the same as that described in paragraph
14-5d. The preferred procedure, time and tactical situation
permitting, is to travel directly from an update point and
determine the mean of two azimuths for each azimuth line
(as a check) by following normal PADS procedures for
determining an azimuth. The azimuths should agree within
0.4 mil. To close out the declination station survey, update
as soon as possible and record adjusted data. Record and
include measured vertical angles with the declination station
data. (The vertical angle is not used with PADS but will
be used at the declination station to determine a vertical
angle correction when the aiming circle is declinated.)
b. Using the PADS With Assumed Data. The PADS
can be operated in areas where known survey control or
GPS data are not available. In such cases, the PADS operator
must know the spheroid and UTM grid zone and must use
all existing support elements (S2, SPCE) to determine the
data needed to initialize the system. The initialization data
used should be as accurate as possible. When conducting a
PADS operation under these conditions, the PADS operator
will update the system over the initialization point (assumed
point) and all control will be extended from this point to
ensure all elements are on a common grid. To close out this
type of survey, the PADS must be updated over the
initialization-initial update point (assumed SCP). This
procedure should be used only in special missions where
known survey control is not available.
c. PADS Operation at Night. The PADS can be operated
at night under blackout conditions as long as the CDU
keyboard can be read with the lamps dimmed or with a
flashlight with strict light control. Only the CDU status
indicators and data display can be dimmed. The keyboard
is either fully illuminated or dark. If autoreflection is to be
performed, the theodolite front sight can be painted white
with typewriter correction fluid or can be illuminated with
the hand lamp. The end of the azimuth line must be
illuminated. Under blackout conditions, the two-position
mark method is preferred in establishing an azimuth line.
The only illumination required for this method is to aid in
marking the station. For tactical reasons, the PADS team
must be thoroughly familiar with all indicators and controls
and the CDU keyboard.
d. PADS Decontamination. While in a survey mission, the
PADS can continue to operate in a nuclear, biological,
chemical (NBC) environment with partial decontamination,
To partially decontaminate the system, the PADS operator
should use the M13 decontamination kit. The CDU, plumb
bob arm, porro prism cover, circuit breaker covers, flashlight,
and battery box latches should be decontaminated. When
the survey mission is complete and the unit has established
a decontamination point, the entire system can be
decontaminated with soapy water. When the entire system
is to be decontaminated, extreme caution must be used to
prevent exposing the system to high-pressure water. The
PADS operator also must ensure that the circuit breaker
covers are closed and that any unconnected cable connector
is capped or taped.
9-5
C1, FM 6-2
*CHAPTER 10
FORWARD ENTRY DEVICE METEOROLOGICAL/SURVEY
The FED MSR is a digital communications device that allows the artillery
surveyer to process command and control information and to perform the
full range of calculations that are currently performed by the BUCS (Survey
REV 1 and DDCT modules). The FED MSR also gives the surveyor
limited forward observer capabilities and graphics that will allow the user
to display tactical symbols and other graphical information.
Section I
OVERVIEW
When properly prepared for operation, the FED MSR is configured to allow surveyors to choose
the survey option desired. The surveyor can perform limited forward observer functions and can
manipulate and display maneuver and fire support information.
10-1. SYSTEM CONFIGURATION
a. The basic device for the FED MSR is the simplified
hand-held terminal unit (SHTU). (See Figure 10-1.) The
quantity authorized to survey elements is the same as the
current authorization for the BUCS (Table 12-1, page 12-1).
b. The FED MSR is issued with a printer (printer, automatic
data processing), Cables are included for connection to a
communications device, printer, and external power source.
c. The FED MSR is powered with an internal battery (BA
5800/U lithium) or external 24 v DC (vehicle) power source.
The average life of the BA 5800/U battery is 18 hours.
d. The FED MSR has a continuous memory capability. This
allows for the retention of data base information while the
device is turned off.
Note. See TM 11-7025-300-10 for warning and
safety statements concerning use of the BA 5800/U
lithium battery. See TM 11-7025-311-12&P for
caution and warning statements concerning
connection of the printer.
h. The SHTU will accept forward observer command and
control (FOCC) application software and MSR software. The
memory capabilities of the SHTU does not allow for loading
more than one application. THE MSR is the software the
surveyor should use. If FOCC software is loaded, it will
need to be erased and MSR software installed. See TM
11-7025-300-10, Chapter 2, for detailed upload-download
procedures.
Figure 10-1. FED MSR (SHTU)
e. The screen of the SHTU is a dot matrix liquid crystal
display. It is capable of displaying 25 lines of information.
The device has a screen saver that blanks the screen after
30 seconds of nonuse.
f. The device has an audible alarm. It alerts the oeprator
when a message has been received or an error has been
made.
g. The alphanumeric keyboard is arranged like a standard
computer keyboard with additional special function keys.
TM 11-7025-300-10, Chapter 1, explains use of the function
keys.
10-1
C1, FM 6-2
Note. If upload-download procedures fail using
MSR.TLF as the file name, rename the ADA_HEAP
file (see Figure 10-2). Then retry according to the
upload-download procedures in the TM. The
renaming of this file will be necessary if the FED MSR
was turned off before exiting the software. To avoid
the renaming procedure, always exit to OPNL
SERVICES before turning off the FED MSR.
10-2.
PREPARATION FOR OPERATION
Before placing the FED MSR into operation as a
communications device, system operational parameters need
to be established. These parameters are entered through the
FED STATUS selection (option J) from the MODE MENU.
The FED STATUS selection provides the operator with the
means to enter information concerning the following:
Local address and observer number of your device.
Type of communications device being used.
Current date and time.
Current FED location.
Map modification data.
Auto target and survey point numbering.
a. Local address and observer number information can be
found in the current signal operation instructions (S0I). To
ensure communications with other elements, member data
(address, observer number, and device type) must be entered.
Member data can be entered by selecting MEMBER DATA
(option F) from the MODE MENU. See TM
11-7025-300-10, Chapter 2, for detailed information on
entering member data. Local SOPs will dictate the elements
that will be entered into the member data table.
b. The FED MSR allows the operator to enter authentication
data required for automatic authentication of messages. The
authentication table provides for the entry of four groups
of authentication codes. Each authentication group can be
assigned a specific destination address. More than one
authentication group can be assigned to one destination
address. Authentication codes are contained in current SOIs.
A two-letter key code is used to verify the use of the
authentication tables. The two-letter key code has to be
entered and verified each time a message is sent by using
the authentication tables. The authentication tables can be
used in the secure or nonsecure mode. Local SOPs will
dictate the use of the authentication tables.
10-3. SURVEY OPTIONS
The SURVEY OPTIONS MENU of the FED MSR gives
the user access to the Survey Control Point File and survey
order functions of the device.
a. The MSR will maintain three survey orders (Received
Survey Order, Working Survey Order, and Issued Survey
Order) in memory at any time. Survey orders can be
maintained in either full five-paragraph form or the
abbreviated two-paragraph form (fragmentary order
[FRAGO]). The issued and received survey orders can be
updated and/or edited by copying them to the Working Copy
file.
b. The Survey Control Point File maintains information on
as many as 360 survey positions. The amount of SCP
information maintained in the data base depends on the
echelon at which the MSR was initialized. The file can be
used to store and transmit firing element information and
SCP data. The Survey Control Point File does not
differentiate between an SCP and a surveyed position. The
Survey Control Point File can be searched by using
parameters identified by the operator and SCP information
transmitted to other members. Members can also search
the Survey Control Point File of other members by
transmitting search criteria. If survey position information
is entered into the file by using geographic coordinates
(latitude and longitude), the device will automatically convert
the geographic coordinates to UTM coordinates and enter
the data in the easting and northing fields of the survey
point message.
Figure 10-2. Renaming the ADA_HEAP file
10-2
C1, FM 6-2
10-4. FORWARD OBSERVER
OPERATIONS
Forward observer messages are found under the MESSAGE
TYPE (option I) selection from the MAIN MENU. Forward
observer messages can also be accessed from the LOCAL
MISSION FILE. These messages permit the operator to
direct engagement of enemy targets by indirect fire and to
transmit and/or receive battlefield information messages.
Detailed information on the use and capabilities of these
messages can be found in TM 11-7025-300-10, Chapter 3.
10-5.
GRAPHICS CAPABILITIES
The graphics of the FED MSR allow the operator to
manipulate and display maneuver and fire support
information stored in the data base. The user identifies the
map area that will be displayed by entering minimum and
maximum easting and northing values in the MAP
MODIFICATION DATA under the FED STATUS selection
from the MODE MENU. Information entered into the Unit
List, Equipment List, Geometry List, and Point/Installation
List files will be displayed on the graphics map. Information
listed in the Member Data File and Survey Control Point
File will also appear on the graphics map. The graphics
map uses icons to display and identify information on the
graphics map. The icons represent military symbols that
can be found in FM 101-5-1. The graphics map displays
information based on the map level that is present on the
graphics map. There are four different map levels available
in the FED MSR. Each map level displays a different set
of icons. Some icons will be visible at more than one map
level. The icons that appear at each of the map levels are
listed in TM 11-7025-300-10, Appendix C. The graphics
map will display an area ranging from 1,000 meters to 99,999
meters, with a default setting of 8,000 meters. TM
11-7025-300-10 provides detailed information on the use of
the graphics map.
Section II
SURVEY CALCULATIONS WITH THE FED MSR
The survey calculations function of the FED MSR allows the operator to perform various types
of survey calculations without performing any setup procedures as described in Section I. The
type of survey calculation desired is selected from the SURVEY CALCULATIONS MENU (Figure
10-3). The FED MSR will maintain up to three completed calculations in its data base for each
type of calculation. Completed calculations are automatically saved in the data base. Records
remain in the data base until the operator either deletes or writes over the record. The device will
allow the operator to establish a new calculations record or to view and/or edit an existing one.
Figure 10-3. SURVEY CALCULATIONS MENU
10-3
C1, FM 6-2
10-6. SURVEY CALCULATIONS
a. FED MSR Forms. The FED MSR calculation forms
were designed to be similar to the BUCS forms to simplify
their use. There are five major parts to the forms:
Administrative data.
Instructions.
Required fields.
Data record.
Remarks.
Some of the forms have additional information on the back.
The use of the different parts of the FED MSR forms and
the procedures for computing them are discussed below.
(Detailed instructions for the use of the FED MSR are in
TM 11-7025-300-10.)
(1) Administrative data. At the top of the form, right
below the form title, there are six blocks. These blocks are
used to record administrative data. When conducting survey
operations, all required information must be entered. This
will ensure that proper records of survey operations can be
maintained.
(2) Instructions. Below the administrative data blocks are
the instructions for the use of the form, to include the
following:
How to call up the required computation.
How to determine what field data are required.
How to display the window of legal entries.
How to calculate the data.
(3) Required fields. On the left side of the form, under the
instructions, are the required fields blocks. These blocks
show which fields appear in the computation. This part of the
form also shows where to record computed data.
(4) Data record. To the right of the required fields blocks
are the data record blocks. These blocks show where to enter
field data (blocks marked with a filled-in arrow). They are
used for recording station names and computed data.
(5) Remarks. This block is located under the required
fields blocks and is provided to record any remarks that are
pertinent to the survey being computed. There are no
particular remarks that are required; however, any
information that could affect the survey should be included.
b. Selecting a Calculation. Once a calculation has been
called up from the SURVEY CALCULATION MENU by
pressing the key that corresponds to the desired calculation,
the summary list for that particular calculation will appear.
(1) To select an empty file (one without a name or main
points), whether it be A, B, or C, select the empty file by
pressing the corresponding letter. For example, if A and B are
full, then select C.
10-4
(2) To delete a file if they are all full, the operator can
select one of the full files by pressing the corresponding letter.
When the calculation screen appears, delete only the one file
by pressing the X key.
(3) To delete the entire list, press the X key at the
Summary List screen. All files for that particular calculation
will be permanently deleted.
c. Entering Data. Once a calculation has been selected
and the applicable DA form has been filled in, the next
steps are to enter field data and record the computed data.
When the calculation is initially called up, the first required
field will be highlighted in black.
(1) When entering data into any of the calculation
programs, all fields that are followed by a question mark (?)
must have an entry. If any question marks remain when the
user tries to perform the calculation, the program will error
and return to the step containing the question mark.
(2) The FED MSR will not accept data into the
computation unless the window of legal entries is displayed
on the screen. The ENTER key acts as a toggle for displaying
the window of legal entries, which shows the range of values
that can be entered in any field. TM 11-7025-300-10, Section
5, and Appendix B list the legal values for all required entries.
The window must be displayed before trying to enter or edit
data in a specific field.
(3) Entry of data is in a fixed format that requires the
operator to complete all available characters for all fields.
This requirement uses preceding and ending zeros for values
that do not include the full range of characters provided. for
example, when entering northing data, there are eight required
digits to the left of the decimal; therefore, you must enter a
zero (unless near the equator) before entering the normal
seven-digit northing. When naming stations, you would have
to fill in the remaining ?s with spaces if the name is not as long
as the required field.
(4) When a field is completely filled in, the next field will
automatically be highlighted and the window will still be
displayed. You can also toggle between fields by using the
up and down arrows to check your data or to edit data already
entered. The ENTER key must be pressed before the C key
for calculating is pressed so that the window of legal entries
is removed. If this is not done, the FED MSR will not respond.
d. Editing Calculations. When the need to edit a
calculation arises (for example, rerunning a survey or
converting to common control), you can edit the calculation
while still in the calculation or by recalling it.
(1) To edit the calculation from the solution screen, press
the S key to show input data. The first screen of entered
data will appear. To move through the calculation within
the pages, use the PG UP or PG DN keys and the up and
down arrow keys.
C1, FM 6-2
(2) To edit the data, do the following in order of listing:
Move the cursor until the required field is highlighted.
Press the ENTER key to display the window of legal
entries.
Replace previously entered data with the new data.
When all required fields have been edited, press the C key
to calculate. The display will move to the next page.
Continue to edit data until you reach the solution screen.
(3) To edit a calculation after you have left it, you must
recall the calculation from the Summary List. Once you recall
the calculation, the solution screen will appear. You then
follow the same procedures as when you were originally in
the calculation.
e. Special Operations. When computing with the FED
MSR, there are several options available when in a
calculation. At the bottom of the screen, there is a list of
options with the key to press to activate the option.
(1) One such option is ACCESS SCP FILE (A key). This
function is used when the SCP file contains the data for the
known control being used in a particular calculation. For
example, when computing a resection and one or more of the
known points (left, center, right) are in the SCP files, you can
retrieve the data and input them into your calculation by
pressing the A key. Once in the Survey Control Point File,
you can select from the list or perform a search to find known
points to use for your calculation.
(2) Another option when computing a survey is the PREV
return function. When you press the PREV key from within
a calculation, you will return to the Summary List. When you
press the PREV key from the Summary List, you will return
to the SURVEY CALCULATIONS MENU and you can
restart operations.
(3) As previously mentioned, you can use the X delete
function to delete the calculation if you need a blank record.
However, the data will be lost.
10-7.
AZIMUTH AND DISTANCE
CALCULATION FILE
a. The Azimuth and Distance Calculation File is designed
to compute the grid azimuth and distance between two
stations. The user must input the known UTM coordinates
of both stations, or select points from the Survey Control
Point File to be imported into the Azimuth and Distance
Calculation File. (See TM 11-7025-300-10, page 5-37, for
step-by-step procedures.)
b. DA Form 7356-R (Computation of Azimuth and Distance
From Coordinates (FED MSR)) (Figure 10-4) is used to
record the data determined. The instructions for computing
the data for this program are shown on the front of the
form.
10-8. TRAVERSE CALCULATION FILE
a. The Traverse Calculation File is designed to compute
the grid azimuth, coordinates, and height of up to 40 main
scheme traverse stations and 10 offset points from the known
data of the starting station and the field data of the traverse.
The program allows for entry of either slope or horizontal
distance. If slope distance is entered, the program does a
conversion to horizontal distance. The program allows the
user to access the Survey Control Point File to import
information for the starting point. The program computes
closing data to include the following:
Azimuth correction.
Height correction.
Total traverse length.
Radial error.
Accuracy ratio.
Traverse adjustment is computed by pressing the T key at
the CLOSURE SOLUTION screen. A list of traverse points
can be displayed by pressing the P key from the CLOSURE
SOLUTION screen of a completed traverse. The list of
traverse points displays adjusted data if the survey was
adjusted. If the survey was not adjusted, unadjusted data
are displayed. (See TM 11-7025-300-10, page 5-40, for
step-by-step procedures.)
b. DA Form 7357-R (Computation of Coordinates and
Height From Azimuth, Distance, and Vertical Angle (FED
MSR)) (Figure 10-5) is used to record the data determined.
The instructions for computing the data for this program
are shown on the front of the form. Closure and adjustment
data are recorded on the reverse of DA Form 7357-R (Figure
10-6).
10-9. TRIANGULATION
CALCULATION FILE
a. The Triangulation Calculation File computes coordinates,
height, azimuth, and distance by triangulation. The program
will compute a single triangle or a chain up to 40 triangles.
The program allows access to the Survey Control Point File
for importing data for the starting point. When entering
the name of the starting station, the user identifies the starting
point as B or C. This step is where the program determines
the side to be computed for the first triangle of a chain.
For the first triangle, the user must also identify the side to
be computed for the next triangle of the chain (prompt NEXT
TRI BASE BA/CA). As the computation continues, this
step is repeated (enter the side to be computed for next
triangle). When entering data for the last triangle in a chain
or a single triangle, enter either BA or CA (the side to be
computed for the last triangle was entered in the previous
triangle) at the prompt NEXT TRI BASE BA/CA. The
program will not compute a triangle without an entry in
this field. (See TM 11-7025-300-10, page 5-45, for
step-by-step procedures.)
10-5
C1, FM 6-2
Figure 10-4. Sample DA Form 7356-R
10-6
C1, FM 6-2
Figure 10-5. Sample DA Form 7357-R
10-7
C1, FM 6-2
Figure 10-6. Sample DA Form 7357-R (reverse)
10-8
C1, FM 6-2
b. DA Form 7358-R (Computation of Plane Triangle
Coordinates and Height From One Side, Three Angles, and
Vertical Angle (FED MSR)) (Figures 10-7 and 10-8) is used
to record the data determined. The instructions for computing
the data for this program are shown on the front of the form.
Closure and adjustment data are recorded on the reverse of
DA Form 7358-R (Figure 10-9).
(A list of star names and numbers are located on the back of
the form.) The program determines accuracy and mean azimuth
in the same manner as the Altitude Method (Sun) Calculation
File program. Access to the Survey Control Point File and
rejected data are controlled in the same manner as the Altitude
Method (Sun) Calculation File. (See TM 11-7025-300-10, page
—
5-58, for step-by-step procedures.)
10-10. RESECTION CALCULATION FILE
Notes.
1. Altitude Method (Sun and Star) Calculation Files
computations will be recorded on DA Form 7360-R
(Figures 10-11 and 10-12). (A list of stars is on the
back of the form [Figure 10-13]).
2. Both Altitude Method Calculation Files require the
entry of OBS DATE, OBS TIME, DAYLT SAVINGS
TIME, and TIME ZONE CORRECTION. This
information is used to determine if the sun or selected
star is in position to meet the prime vertical
requirements (Chapter 7, paragraph 7-11e). If the
prime vertical requirements are not met, the status
line will display SUN/STAR NOT WITHIN 530 MILS
OF PRIME VERTICAL. The status line will also
display a warning (VERTICAL ANGLE TO
SUN/STAR NOT BETWEEN 175 AND 800 MILS)
when the vertical angle does not fall between 175 and
800 mils. The programs will perform the calculation
and provide a solution even if either or both of these
conditions exist.
a. The Resection Calculation File computes the coordinates
and height of one or more stations from the UTM coordinates
of three known stations and the azimuth from the occupied
station to the center station. The program allows the user access
to the Survey Control Point File for importing data of the three
known points. (See TM 11-7025-300-10, page 5-51, for
step-by-step procedures.)
b. DA Form 7359-R (Computation of Coordinates and Height
by Three-Point Resection (FED MSR)) (Figure 10-10) is used
to record the data determined. The instructions for computing
the data for this program are shown on the front of the form.
10-11. COMPUTATION OF ASTRONOMIC
AZIMUTH BY ALTITUDE METHOD
(SUN AND STAR)
a. Altitude Method (Sun) Calculation File. This program
computes a grid azimuth to an azimuth mark from three sets
of observations of the sun. The program provides the user
with a mean astronomic and grid azimuth. The program
compares each of the azimuths to the mean to determine if
the observation meets required accuracies. If one of the sets
does not meet the rejection criteria, an audible alarm sounds
and the status line will display: OBSERVATION SET _
REJECTED. If two of the sets fail to meet the rejection criteria,
the audible alarm will sound and the status line will display:
TWO OR MORE OBSERVATION SETS REJECTED.
RERUN OBSERVATIONS. The audible alarm can be silenced
and the status line cleared by pressing the NEXT (F8) key.
The user can access the Survey Control Point File to import
location data for the observing station only if the latitude and
longitude are entered in the Survey Control Point File. If the
geographic location is not entered in the Survey Control Point
File, the program will display NO APPLICABLE SURVEY
POINTS AVAILABLE FOR ACCESS. (See TM
11-7025-300-10, page5-55, for step-by-step procedures.)
Note. The last prompt in the initiation screen is
DAYLT SAVING TIME (Y/N). It does not matter what
is entered at the DAYLT SAVING TIME (Y/N) prompt;
the calculation does not use this information. The
user must enter the time zone correction, to include
daylight savings time, at the TIME ZONE
CORRECTION prompt for the calculation to correctly
compute the azimuth.
b. Altitude Method (Star) Calculation File. This program
computes a grid azimuth to an azimuth mark from three sets
of observations of a selected star. The user must enter the
number of the star being used at the STAR NO/NAME prompt.
10-12. HASTY ASTRO CALCULATION
FILE (SUN AND STAR)
a. Hasty Astro (Sun) Calculation File. This program
computes a grid azimuth and check angle from observations
of the sun. The program uses an internal electronic ephemeris,
which eliminates the need to extract data from FM 6-300. The
program also provides the option to use the internal clock (see
arty astro method) of the device to determine the date and
time of tip. Date and time can also be entered manually. The
ability to manually input date and time of observation allows
the computation to be performed at a site remote from where
the fieldwork is performed. The Survey Control Point File
can be accessed from the program. This allows data for the
position of the observation to be imported directly into the
computation (the latitude and longitude must be included in
the Survey Control Point File). (See TM 11-7025-300-10, page
5-62, for step-by-step procedures.)
b. Hasty Astro (Star) Calculation File. This program
computes a grid azimuth and check angle from observations
of survey stars. The user must enter the number of the star
being used at the STAR NO/NAME prompt. The program
has the same capabilities as the Hasty Astro (Sun) program.
(See TM 11-7250-300-10, page 5-65, for step-by-step
procedures.)
Note. DA Form 7361-R (Computation of Astronomic
Azimuth by the Hasty Astro Method (FED MSR))
(Figure 10-14) is used to record the data determined.
The instructions for computing the data to be
recorded are shown on the front of the form. A list of
star names and numbers is located on the back of the
form (Figure 10-15).
10-9
C1, FM 6-2
Figure 10-7. Sample DA Form 7358-R
10-10
C1, FM 6-2
Figure 10-8. Sample DA Form 7358-R (page 2)
10-11
C1, FM 6-2
Figure 10-9. Sample DA Form 7358-R (reverse)
10-12
C1, FM 6-2
Figure 10-10. Sample DA Form 7359-R
10-13
C1, FM 6-2
Figure 10-11. Sample DA Form 7360-R for Star
10-14
C1, FM 6-2
Figure 10-12. Sample DA Form 7360-R for Sun
10-15
C1, FM 6-2
Figure 10-13. Sample DA Form 7360-R (reverse)
10-16
C1, FM 6-2
Figure 10-14. Sample DA Form 7361-R
10-17
C1, FM 6-2
Figure 10-15. Sample DA Form 7361-R (reverse)
10-18
C1, FM 6-2
10-13. STAR ID CALCULATION FILE
a. The Star ID Calculation File computes the approximate
azimuth and altitude to a selected star at a date and time
chosen by the user. The orientation data will help identify
survey stars for astronomic observation or navigation. The
program will compute the approximate azimuth and altitude
(vertical angle) to any of the 73 survey stars listed in FM
6-300. The orientation data are accurate to within 5 mils.
(See TM 11-7250-300-10, page 5-71, for step-by-step
procedures.)
b. DA Form 7362-R (Computation of Azimuth and Vertical
Angle to Selected Star (Star ID) (FED MSR)) (Figure 10-16)
is used to record the data determined. The instructions for
computing the data to be recorded are shown on the front
of the form.
10-14. POLARIS TABULAR METHOD
CALCULATION FILE
a. The Polaris Tabular Method Calculation File computes
a grid azimuth from three sets of observations of the star
Polaris, using the Polaris Tabular method. The program
checks the accuracy specifications in the same manner as
described for the altitude method (paragraph 10-11). (See
TM 11-7025-300-10, page 5-75, for step-by-step procedures.)
b. DA Form 7363-R (Computation of Astronomic Azimuth
by Polaris Tabular Method (FED MSR) (Figure 10-17) is
used to record the data determined. The instructions for
computing the data to be recorded are shown on the front
of the form.
10-15. GRID CONVERGENCE
CALCULATION FILE
a. The Grid Convergence Calculation File converts a UTM
grid azimuth from a gyroscopic (true) azimuth. The program
also computes the convergence from true to grid azimuth
for an area of operations. (See TM 11-7250-300-10, page
5-78, for step-by-step procedures.
b. DA Form 7364-R (Computation--Convergence of True
Azimuth to Grid Azimuth (FED MSR)) (Figure 10-18) is
used to record the data determined. The instructions for
computing the data to be recorded are shown on the front
of the form.
10-16. TRIG TRAVERSE
CALCULATION FILE
a. The Trig Traverse File computes horizontal distances and
comparative accuracy from trig-traverse fieldwork. (See TM
11-7025-10, page 5-90, for step-by-step procedures.)
Note. M=SUBTENSE is no longer used and will be
removed from the next version.
b. DA Form 7365-R (Computation of Trig Traverse (FED
MSR)) (Figure 10-19) is used to record the data determined.
The instructions for computing the data to be recorded are
shown on the front of the form.
10-17. INTERSECTION
CALCULATION FILE
a. The Intersection Calculation File computes the coordinates
and height of an unknown point (target) from intersection
fieldwork. The program can be used for either intervisible
or nonintervisible bases. The Survey Control Point File can
be accessed from the initiation screen. This program has
the capacity to store 40 targets for three sets of OPs. For
example, in file A= from the two selected OPs, the program
will store data for 40 targets. The same amount of targets
can be stored in files B= and C= regardless of whether the
OPs are the same or one or both are new OPs. If additional
targets are required from the same two OPS, press the next
open target record (that is, B=), enter data, confirm data,
and press the C key. Continue to record target data and
select open target records until all targets have been computed.
If more than 40 targets are required, then go to Summary
List. Select a blank file, and start a new calculation. (See
TM 11-7025-300-10, page 5-96, for step-by-step procedures.)
b. DA Form 7366-R (Computation of Coordinates and
Height by Intersection (FED MSR)) (Figure 10-20) is used
to record the data determined. The instructions for computing
the data to be recorded are shown on the front of the form.
10-19
C1, FM 6-2
Figure 10-16. Sample DA Form 7362-R
10-20
C1, FM 6-2
Figure 10-17. Sample DA Form 7363-R
10-21
C1, FM 6-2
Figure 10-18. Sample DA Form 7364-R
10-22
C1, FM 6-2
Figure 10-19. Sample DA Form 7365-R
10-23
C1, FM 6-2
Figure 10-20. Sample DA Form 7366-R
10-24
C1, FM 6-2
10-18. ARTY ASTRO CALCULATION
FILES (SUN AND STAR)
a. Arty Astro Observation (Sun). This program computes
a grid azimuth from three observations of the sun. This
program uses an internal electronic ephemeris, which
eliminates the need to extract data from FM 6-300. The
program provides the option of using the internal timer or
manually entering the date and time of tip for each
observation.
(1) To use the internal timer, the correct date and accurate
time must be entered during the FED STATUS setup as
mentioned in Section I. If the time module is selected, the
DETERMINE TIP OF OBSERVATION screen will appear.
When tip is determined, press the K key.
(2) The user also has the option to press the N key and
return to the initiation screen. The user can then select not
to use the time module. The ability to manually input date
and time of observation allow the fieldwork to be performed
without the FED MSR being at the site of observation. The
user can access the Survey Control Point File to import
location data for the observing station only if the latitude
and longitude are entered in the Survey Control Point File.
If the geographic location is not entered in the Survey Control
Point File, the program will display NO APPLICABLE
SURVEY POINTS AVAILABLE FOR ACCESS. The
program checks the accuracy of the observation in the same
manner as described in the altitude method (paragraph 10-11).
(See TM 11-7250-300-10, page 5-81, for step-by-step
procedures.)
b. Arty Astro Observation (Star). This program computes
a grid azimuth from three observations of any survey star.
This program functions the same as the Arty Astro Sun
program with the exception that it computes azimuth from
observations of survey stars. The program will compute
the azimuth from any of the 73 survey stars listed in FM
6-300. (See TM 11-7250-300-10, page 5-85, for step-by-step
procedures.)
c. DA Form 7367-R. DA Form 7367-R (Computation
of Astronomic Azimuth by the Arty Astro Method (FED
MSR)) (Figure 10-21) is used to record the data determined.
The instructions for computing the data to be recorded are
shown on the front of the form. The star names and numbers
are located on the back of the form (Figure 10-22).
10-25
C1, FM 6-2
Figure 10-21. Sample DA Form 7367-R
10-26
C1, FM 6-2
Figure 10-22. Sample DA Form 7367-R (reverse)
10-27
C1, FM 6-2
Section Ill
CONVERSION AND TRANSFORMATION WITH THE FED MSR
The transformations function of the FED MSR will allow the operator to perform various types
of survey conversions and transformations. The type of transformation desired is selected from
the TRANSFORMATIONS MENU (Figure 10-23). The FED MSR will maintain up to three
completed calculations in its data base for each type of transformation. Completed calculations
are automatically saved in the data base. Records remain in the data base until the operator either
deletes or writes over the record. The device will allow the operator to establish a new calculation
record or view or edit an existing one.
10-19. TRANSFORMATIONS
The transformations function of the FED MSR will allow
the operator to perform conversion of UTM coordinates to
geographic coordinates and geographic coordinates to UTM
coordinates. It also provides for zone-to-zone transformation
of coordinates and azimuth and datum-to-datum coordinate
transformations. The FED MSR transformation forms and
calculation procedures were designed to be similar to the
FED MSR survey calculations to simplify their use. See
Section II, paragraphs 10-6a through e, for an explanation
of the following:
How different parts of the FED MSR forms are
used.
How to select a calculation.
How to enter data.
How to edit a calculation.
How to perform various special operations.
Detailed instructions for the use of the FED MSR are in
TM 11-7025-300-10. For further reference, conversions and
transformations are discussed in Chapter 11.
Figure 10-23. TRANSFORMATIONS MENU
10-28
C1, FM 6-2
10-20. UTM TO GEO COORDINATE
CONVERSION FILE
a. This program converts UTM coordinates to geographic
coordinates. The Survey Control Point File can be accessed
from this calculation. (See TM 11-7025-300-10, page 5-100,
for step-by-step procedures.)
b. DA Form 7368-R (Computation--Conversion UTM to
GEO Coordinate, GEO to UTM Coordinate, Zone-To-Zone
Transformation (FED MSR)) (Figure 10-24) is used to record
the data determined. The instructions for computing the
data to be recorded are shown on the front of the form.
10-21. GEO TO UTM COORDINATE
CONVERSION FILE
a. This program converts geographic coordinates to UTM
coordinates. The Survey Control Point File cannot be
accessed from this calculation. (See TM 11-7025-300-10,
page 5-103, for step-by-step procedures.)
b. DA Form 7368-R is also used for recording the GEO to
UTM coordinate conversion data. (See Figure 10-24.)
10-22. ZONE-TO-ZONE COORDINATE
CONVERSION FILE
a. This program, also refered to as zone-to-zone
transformation, transforms UTM grid coordinates and
azimuth from one grid zone into terms of an adjacent grid
zone. The Survey Control Point File can be accessed from
this calculation. (See TM 11-7025-300-10, page 5-106, for
step-by-step procedures.)
b. DA Form 7368-R is also used for recording the
zone-to-zone transformation data. (See Figure 10-24.)
10-23. UTM TO UTM DATUM
CONVERSION FILE
a. This program transforms UTM coordinates from a selected
UTM datum to another selected UTM datum. The program
also allows the option of zone-to-zone transformation. If
yes (option Y) is selected, the ending grid zone must be
entered. The datum numbers must be entered (known) for
all calculations. The Survey Control Point File can be
accessed from these calculations. (See TM 11-7025-300-10,
page 5-109, for step-by-step procedures.)
b. DA Form 7369-R (Computation--Datum to Datum
Coordinate Transformation Listed Datums (FED MSR))
(Figure 10-25) is used to record the data determined. The
instructions for computing the data to be recorded are shown
on the front of the form. A list of datum names and
corresponding numbers are located on the back of the form
(Figure 10-26), in Appendix E, and in TM 11-7025-300-10
(pages B-34 through B-37).
10-24. UTM TO GEO DATUM
CONVERSION FILE
a. This program transforms UTM coordinates from a selected
UTM datum to GEO coordinates of a selected GEO datum.
(See TM 11-7025-300-10, page 5-112, for step-by-step
procedures.)
b. DA Form 7369-R is also used for recording data
transformed from UTM to GEO datum. (See Figure 10-25.)
10-25. GEO TO UTM DATUM
CONVERSION FILE
a. This program transforms GEO coordinates from a selected
GEO datum to UTM coordinates of a selected UTM datum.
(See TM 11-7025-300-10, page 5-115, for step-by-step
procedures.)
b. DA Form 7369-R is also used for recording data
transformed from GEO to UTM datum. (See Figure 10-25.)
10-26. GEO TO GEO DATUM
CONVERSION FILE
a. This program transforms GEO coordinates from a selected
GEO datum to another selected GEO datum. (See TM
11-7025-300-10, page 5-118, for step-by-step procedures.)
b. DA Form 7369-R is also used for recording data
transformed from one GEO datum to another. (See Figure
10-25.)
10-27. KRASSOVSKY TO UTM DATUM
CONVERSION FILE
a. Krassovsky to UTM datum coordinate transformations
transform UTM coordinates from a selected Krassovsky
datum to a selected UTM datum. The datum numbers must
be entered (known) for all calculations. (See TM
11-7025-300-10, page 5-121, for step-by-step procedures.)
b. DA Form 7370-R (Computation--Datum-To-Datum
Coordinate Transformation Gauss Kruger (GK) Datums
(FED MSR)) (Figure 10-27) is used to record the data
determined. The instructions for computing the data to be
recorded are shown on the front of the form. A list of
datum names and corresponding numbers is located on the
back of the form (Figure 10-26), in Appendix E, and in TM
11-7025-300-10 (pages B-34 through B-37). The Survey
Control Point File can be accessed from these calculations.
10-29
C1, FM 6-2
Figure 10-24. Sample DA Form 7368-R
10-30
C1, FM 6-2
Figure 10-25. Sample DA Form 7369-R
10-31
C1, FM 6-2
Figure 10-26. Reverseof DA Forms 7369-R, 7370-R, and 7371-R
10-32
C1, FM 6-2
10-28. UTM TO KRASSOVSKY DATUM
CONVERSION FILE
a. UTM to Krassovsky datum coordinate transformations
transform UTM coordinates from a selected UTM datum to
a selected Krassovsky datum. (See TM 11-7025-300-10,
page 5-122, for step-by-step procedures.)
b. DA Form 7370-R is also used to record UTM to
Krassovsky datum coordinated transformation. (See Figure
10-27.)
10-29. BESSEL TO UTM DATUM
CONVERSION FILE
a. Bessel to UTM datum coordinate transformations
transform UTM coordinates from a selected Bessel datum
to a selected Bessel datum to a selected UTM datum. (See
TM 11-7025-300-10, page 5-127, for step-by-step
procedures.)
b. DA Form 7370-R is also used to record Bessel to UTM
datum coordinate transformations. (See Figure 10-27.)
10-30. UTM TO BESSEL DATUM
CONVERSION FILE
a. UTM to Bessel datum coordinate transformations
transform UTM coordinates from a selected UTM datum to
a selected Bessel datum. (See TM 11-7025-300-10, page
5-130, for step-by-step procedures.)
b. DA Form 7370-R is also used to record UTM to Bessel
datum coordinate transformations. (See Figure 10-27.)
Note. When performing a Krassovsky or Bessel to
UTM datum coordinate transformation, the user must
select datums and/or numbers from the box at the top
of the back of DA Form 7370-R. When performing
a UTM to Krassovsky or Bessel datum coordinate
transformation, select datums and/or numbers from the
99 listed datums.
10-31. USER-DEFINED TO
USER-DEFINED DATUM
CONVERSION FILE
a. User-defined to user-defined datum coordinate
transformations transform UTM coordinates from a selected
user-defined datum to another selected user-defined datum.
These programs allow the option of zone-to-zone
transformation. If yes (option Y) is selected, the ending
grid zone must be entered. The Survey Control Point file
cannot be accessed from any of these calculations. (See
TM 11-7025-300-10, page 5-133, for step-by-step
procedures.)
b. DA Form 7371-R (Computation--Datum-To-Datum
Coordinate Transformation User-Defined Datums (FED
MSR)) (Figure 10-28) is used to record the data determined.
The instructions for recording the data determined are shown
on the front of the form. The listed datums for computing
these transformations and datum numbers are located on the
back of the form. This information can also be found in
Appendix E. Also, the Defense Mapping Agency (DMA)
or a higher headquarters will disseminate user-defined datum
parameters when needed.
10-32. USER-DEFINED TO LISTED
DATUM CONVERSION FILE
a. User-defined to listed datum coordinate transformations
transform UTM coordinates from a selected user-defined
datum to a selected listed datum. (See TM 11-7025-300-10,
page 5-139, for step-by-step procedures.)
b. DA Form 7371-R is also used to record user-defined to
listed datum coordinate transformations. (See Figure 10-29.)
10-33. LITSTED TO USER-DEFINED
DATUM CONVERSION FILE
a. Listed to user-defined datum coordinate transformations
transform UTM coordinates from a selected listed datum to
a selected user-defined datum. (See TM 11-7025-300-10,
page 5-142, for step-by-step procedures.)
b. DA Form 7371-R is also used to record listed to
user-defined datum coordinate transformations. (See Figure
10-30.)
10-33
C1, FM 6-2
Figure 10-27. Sample DA Form 7370-R
10-34
C1, FM 6-2
Figure 10-28. Sample DA Form 7371-R (user-defined to user-defined)
10-35
C1, FM 6-2
Figure 10-29. Sample DA Form 7371-R (user-defined to listed)
10-36
C1, FM 6-2
Figure 10-30. Sample DA Form 7371-R (listed to user-defined)
10-37
FM 6-2
*CHAPTER 12
BACKUP COMPUTER SYSTEM
12-1. BUCS CONFIGURATIONS
The BUCS has two configurations-the BUCS General and
the BUCS Special. The quantity and configuration authorized
to survey elements are shown in Table 12-1.
Table 12-1. Authorization to survey elements
a. BUCS General. The BUCS General consists of the
HP71B computer, a carrying case, and reference material.
The HP71B is powered by four AAA 1.5-volt batteries or
through an AC adapter by 120- or 240-v AC current. The
average battery life of the four AAA batteries is 60 hours.
The HP71B can perform rapid and accurate calculations.
The computer has an operating system that accepts any RAM
or read-only memory (ROM) combination to a maximum
of four plug-in custom or prewritten memory modules. It
has a continuous memory that can be expanded with the
use of plug-in memory modules. The continuous memory
allows the operator to turn the computer off and later resume
operation without losing memory programs or the previous
program calculations. The HP71B has a liquid crystal display
that can display up to 22 characters. The contrast of the
display characters and annunciator and the viewing angle
are adjustable. The computer can function as a perpetual
clock and/or calendar.
b. BUCS Special. The BUCS Special consists of the HF71B
computer, the HP2225B ThinkJet printer, the interface cable,
the HP-IL 82401A interface module, the HP2225B battery
pack, a 120-volt and a 240-volt AC adapter, the carrying
case, and reference material. (See Figure 12-1.) The
ThinkJet printer is designed for portability. It is powered
by a rechargeable battery pack or by a 120- or 240-v AC
adapter. The print head cartridge in the ThinkJet printer is
disposable and easy to replace. The printer is designed to
print on standard 8.5- by 11-inch or European size A-4
single-sheet or fanfold paper. It can print 150 characters
per second, print bold characters, and underline in four print
pitches.
Figure 12-1. BUCS with components
12-1
FM 6-2
12-2. ALPHANUMERIC KEYBOARD
FUNCTIONS
Most keys on the computer perform one primary operation
and two alternate operations. The primary operation of any
key is indicated by the white or black character(s) on the
face of the key. The alternate operations are indicated by
the gold characters printed above the keys and the blue
characters below the keys. To select the character or
operation printed on the face of a key, press only that key.
To select the alternate character or operation printed in gold
and blue, press the like-colored prefix key f or g and then
the operation key. The functions of each key are described
in TM 9-7000-200-13&P and the HP71B Reference Manual.
12-3. STATUS ANNUNCIATORS
Table 12-2 lists and briefly describes the status annunciators.
(3) Turn the computer off before installing or removing
plug-in modules. Memory loss will occur if the interface
module or a RAM or ROM module is removed when the
computer is on.
(4) Turn the computer and printer off before connecting
or disconnecting the interface cables to either component.
(5) Do not place the computer in strong magnetic fields
(for example, near a telephone).
(6) Do not place fingers, tools, or other foreign objects
into any of the computer plug-in ports.
(7) Place the printer on a clean and level surface for
operation.
b. BUCS Turn-On and Turn-off Procedures. To place
the computer in operation, press the ON key. To turn the
computer off, perform one of the following:
Ž Press the f key and then the ON key.
Table 12-2. Status annunciators
DISPLAY
BAT
MEANING
Battery is low.
CALC
HP71B is in the calculate mode.
USER
User keyboard is active.
RAD
Angular setting is radians.
PRGM
A program is running.
SUSP
A program is suspended.
Data extend to the left 01 the display,
Data extend to the right of the display.
12-4. PREPARATION FOR BUCS
OPERATION
a. BUCS Operating Precautions. Certain electronic
circuits in the computer function continuously. Improper
operation can disrupt performance in unexpected ways or
damage the electronics. Observe the precautions below in
assembling or operating the BUCS General or BUCS Special.
(1) When installing batteries or RAM or ROM modules,
the operator must ground himself to metal to remove static
electricity from the computer. This is particularly important
for the handling of the HP-IL 82401A interface module.
(2) Turn the computer off before installing or removing
batteries. When removed, the batteries must be replaced
within 30 seconds or the contents of the computer memory are
lost. If the AC adapter is connected to the computer, the
memory will not be lost when the batteries are changed.
12-2
Ž Type in OFF, and press the END LINE key.
Ž Type in BYE, and press the END LINE key (only in
basic mode).
Note. A power supply safeguard automatical turns
the computer off with loss of memory after 10
minutes of inactivity.
c. BUCS General Assembly. To use the BUCS General
for survey computations, perform the steps discussed below.
(1) Ensure the computer is off. No prompts or characters
should appear in the display window.
(2) Turn the computer upside down, and set it on a soft,
flat surface.
(3) Using your thumb, press down on the battery
compartment door (the door to the center compartment).
Slide the compartment door toward the rear of the computer.
When you press down on the compartment door, the catch will
snap as it unlatches from the computer.
(4) Insert the batteries. Be careful to align the batteries
according to the indicators in the compartment. (See Figure
12-2.)
Figure 12-2. HP71B battery installation
FM 6-2
(5) Lay the compartment door imposition. Slide it toward
the front of the computer until the catch snaps.
Figure 12-4. HP-IL 62401A interface installation
(6) Insert and secure the program ROM module in the
appropriate plug-in port on the computer. Port 1 is the
preferred port to use. If port 1 is in use, take the next
numbered port. (See Figure 12-3.)
Figure 12-3. Survey ROM module installation
Figure 12-5. HP71B interface cables
CAUTION
Inserting or retrieving the program ROM module while
the computer is on can damage the module and/or
cause the display to be frozen.
d. BUCS Special Assembly. The computer for the BUCS
Special is assembled in the same manner as that for the
BUCS General. To use the printer with the computer, follow
the procedures discussed below.
Figure 12-6. HP2225B printer (rear view)
(1) Insert and secure the HP-IL 82401A interface module
in the appropriate plug-in port on the computer. (See Figure
12-4.)
(2) Connect the interface cables to the interface module
connectors of the computer. (See Figure 12-5.)
(3) connect the interface cables to the printer interfaee
connectors. (See Figure 12-6.)
(4) Insert the battery pack into its slot on the printer.
Push the battery pack inward until the latch snaps shut.
(5) Insert the AC adapter plug into the receptacle on
the battery pack; then connect the AC adapter to the AC
power source.
(6) To turn the printer on, press the POWER switch to
the 1 position. The PWR light should be on.
12-3
FM 6-2
(7) Open the front cover of the printer, and pull back
the carriage latch. Insert the paper ink absorber into its
holder. Insert the print head cartridge into the carriage. (See
Figure 12-7.)
(8) Close and snap the carriage latch, and pull the bail
arm back. Install the paper separator onto the printer, and
raise it to the vertical position. (See Figure 12-7.)
(9) Insert the paper, and slide it along the paper channel
into the slot under the paper separator. Pull the top edge
of the paper 1/4 inch above the bail arm rollers.
(10) Align the right-hand pinwheel to the paper holes,
and push the bail arm forward. Lower the paper separator
to the operating position, and close the printer cover. The
BUCS Special is now ready for operation.
e. HF71B Computer Operational Self-Test. The self-test
can be conducted with or without the AC adaptor. If you
suspect that the computer is not operating properly, perform
the self-test as specified below.
Figure 12-7. HP2225B printer (front view)
Note. It is advisable to perform the self-test after
prolonged periods of storage or when installing new
batteries and/or ROM modules.
(1) Turn the computer off.
(2) Remove all custom or prewritten program ROM
modules from the computer. Reinsert the plug-in port covers
into the computer plug-in ports.
(3) Plug the AC adapter into the receptacle on the back of
the computer. Connect the AC adapter to an AC power outlet.
(4) Turn the computer on.
(5) Type PI, and then press the END LINE key. The result
3.14159265359 should be displayed, which indicates that
about 60 percent or more of the computer circuits are
operating properly.
(6) If the computer repeatedly fails to perform a particular
operation or repeatedly displays an error message, such as
EXCESS CHARS, carefully reread the instruction regarding
that operation. You may be improperly specifying the
operation.
(7) If the computer still does not operate properly, press
the ON key and / key at the same time. INIT:1 will appear
in the display. Press the END LINE key to execute a Level 1
initialization. The display should now display the replace
cursor (BASIC mode) or insert cursor (CALC mode).
(8) Press the ON key and/ key at the same time. Then
press the 2 key and END LINE key. This executes a Level
2 initialization (INIT: 2). The computer will do a self-test
of its circuitry and will display ROM TEST 1 as it begins
to test the circuits. When the first portion of the test verifies
the proper operation of the circuits, the computer will display
ROM TEST 1G 2. This indicates that the computer is
continuing the test. When the test is completed, the computer
will display ROM TEST 1G 2G 3G 4G. Then it will return
to the BASIC mode if the test revealed no faulty circuits.
If faulty circuits are detected, at least one of the numbers
will be followed by a B instead of a G. Thus, ROM TEST
1G 2B 3G 4G indicates that the computer has a faulty ROM.
If the computer indicates a faulty ROM after an INIT: 2
test, it requires service.
(9) If the display remains blank when the ON key is
pressed, or if characters remain “frozen” in the display, then
reset the memory by using the procedure below.
(a) Press and release the ON and / keys at the same
time.
(b) The display prompts INIT: 1. All keys are now
inactive except 1, 2,3, and END LINE. To reset the memory,
press the 3 and END LINE keys.
(c) The display prompts MEMORY LOST. Clear
the display by prosing the ON key.
12-4
FM 6-2
(10) If the procedure outlined in (9) above did not solve
the problem, reset the memory as discussed below.
(a) Unplug the AC adapter, and turn the computer
off.
(b) Remove all modules.
(c) Remove the batteries.
(d) Press and hold down the ON key for about 30
seconds to discharge the circuits.
(e) Install the batteries, or connect the AC adapter.
Then press the ON key. The message MEMORY LOST
should appear in the display. Pressing any key should display
the BASIC prompt and replace the cursor.
f. HP2225B ThinkJet Printer Operational Self-Test. If
you suspect that the printer is not operating properly, perform
the self-test in the order specified below.
(1) Turn the HP2225B printer off.
(2) Depress and hold the line feed (LF button while
turning the power switch on.
(3) Release the LF button to start the self-test sequence.
(4) You can terminate the self-test at any time by turning
the printer off.
prompts displayed must be followed step-by-step to
determine the correct data or solution in that program. The
known or field data required for computer computations are
the same as those required for manual computations. Survey
data and computations may be recorded on the appropriate
computation forms developed for use with the computer or
recorded directly by the printer when the BUCS Special
computer is used. The prompt abbreviations are explained
in the Glossary and in the instructions section of each form.
12-5. SURVEY PROGRAM MODULE
(1) Follow the steps in Table 12-3 to call a program for
which the program or module number is known.
The survey programs in the survey program module are
user-friendly. The user is guided through each program by
numerous prompts that are simple and understandable. The
Note. Record data exactly as shown on the display.
Computations will be rounded off only before survey
data are passed to the user.
a. Initial Turn-On. To activate the survey module for the
initial turn-on, type RUN SURVEY; then press the END
LINE key. The display shows SURVEY PGM MENU
REV1. After the initial turn-on, the user need only press
the RUN key to call up the survey program menu. Anytime
the survey module is removed, the initial turn-on procedure
applies.
b. Program Selection. Two different procedures can be
used to select a program from the survey module.
(2) Follow the steps in Table 12-4 to call a program for
which the program or module number is unknown.
Table 12-3. Program or module number known
STEP
1
INSTRUCTION
Initial turn-on
ENTER
RUN SURVEY
2
MODULE #
3
Select module
4
Enter the required Input data, and follow the
program prompts.
PRESS
DISPLAY
END LINE
^DATE 01-JAN-00
END LINE (three times)
MODULE DESIRED-
END LINE
(program title)
Table 12-4. Program or module number unknown
STEP
1
lNSTRUCTION
Initial turn-on
2
3
Select module
ENTER
RUN SURVEY
PRESS
DISPLAY
END LINE
^DATE 01 JAN-00
END LINE (three times)
MODULE DESIRED-
END LINE
(program title)
12-5
FM 6-2
Table 12-4. Program or module number unknown (continued)
STEP
lNSTRUCTION
4
Continue to press END LINE key to obtain next
program or until desired program title and number
are displayed.
5
When desired program title and number are
displayed, press X key and END LINE key.
6
Enter required input data, and follow program
prompts.
ENTER
PRESS
DISPLAY
c. Survey Program Menu. Table 12-5 is a complete list
of the programs contained in the menu as each appears in
the display.
Table 12-5. Survey program menu
TITLE
AZIMUTH/DISTANCE
TRAVERSE
TRlANGULATION
RESECTION
ALT METHOD
HASTY ASTRO
STAR ID
POLARIS TABULAR
CONVERGENCE
CONVERSION/TRANS
SUBT/TRIG TRAV
INTERSECTION
ARTILLERY ASTRO
NUMBER
#1
#2
#3
#4
#5
#6
#7
#8
#9
#10
#11
#12
#13
d. Program Functions. The operator can back Up to or
recall a previous display, or he can go to the top of a file
and review the entire program. He can correct data, if
required, by entering the correct data. The operator can
abort a survey program at any time. These capabilities are
inherent to the survey program software.
(1) Backup. To backup to a prior prompt or data display,
press the Band END LINE keys. To backup to each previous
prompt or data display, repeatedly press the B and END LINE
keys.
Note. Specific display prompts are preceded by a
circumflex (^). The circumflex is used with the
backup function. It tells the operator performin the
backup operation that some data have been
bypassed.
To review the bypassed data, the
operator must proceed in the program.
In the
following example, Program 1, Azimuth and Distance,
is used to demonstrate the backup procedures when
a prompt with a circumflex is displayed.
12-6
(2) Top of file. To go back to the beginning of a program,
press the T (top of file) and END LINE keys. This allows
the operator to review the entire program and check the
data displays to ensure correct information was entered.
(3) Error correction. After performing a backup of a
prior input, the operator can correct input data by entering
the corrected data where the error exists. Key in the correct
data, and press the END LINE key. To recompute all outputs
by using the corrected data, press the END LINE key as
required.
(4) Abort. The operator can abort a survey program at
any point in the program calculation by pressing the A and
END LINE keys. A safety prompt, ABORT (Y/N), is
displayed to preclude accidentally aborting a program. To
complete the abort procedure, press the Y and END LINE
keys. The next display prompt will be SURVEY PGM
MENU REV1.
(5) Warning messages. Table 12-6 lists the warning
messages that may be encountered in the survey programs.
FM 6-2
12-6. SURVEY PROGRAMS
a. Program 1–Azimuth and Distance. This program
computes the grid azimuth and distance between two known
stations. The user must input the known UTM coordinates
of both stations. Computations are recorded on DA Form
5590-R.
b. Program 2–Traverse. This program computes the grid
azimuth, coordinates, and height of up to 40 main scheme
traverse stations from the known data of the starting station
and the field data of the traverse. Offset stations (doglegs)
are not included. The program converts slope distance to
horizontal (sea level) distance and computes total traverse
length, total azimuth and height corrections, radial error of
closure, and accuracy ratio. (See Appendix B for accuracy
requirements.) It also computes traverse adjustment. A
sketch of a sample traverse is shown in Figure 12-8. The
known data and field data to be used in computation of this
traverse are recorded on DA Form 5591-R. The closure
and adjustment data are recorded on the reverse of DA Form
5591-R. The data for a dogleg cannot be recalled for
correction or review after the prompt AZ TO REAR: 0.000
is displayed and the END LINE key is pressed (step 6).
c. Program 3–Triangulation. This program computes
coordinates, height, azimuth, and distance by triangulation.
It will compute a single triangle or a chain of triangles up
to 40 triangles. Data for triangulation computations are
recorded on DA Form 5592-R.
d. Program 4-Resection. This program computes the
coordinates and height of one or more stations from the
UTM coordinates of three known stations. Resection
computations are recorded on DA Form 5593-R.
Figure 12-8. Sketch of a sample traverse
Table 12-6. Warning messages
MESSAGES
INDICATION
FILE FULL
Occurs in traverse,
triangulation, and
intersection when 40
stations or targets are
exceeded.
NO VALID SOLUTION
Occurs in three-point
resection when sum of
angles falls between 2,845
and 3,555.
SET # REJECTED
Occurs in the astronomic
programs when a single set
is rejected.
REJECT CRIT NOT MET
Occurs in the astronomic
programs when rejection
criteria are not met.
MAXIMUM 3 SETS
Occurs when operator tries
to compute more than three
sets of astronomic
computations.
INSUFFICIENT MEMORY
May occur if RAM has not
been cleared before survey
module is inserted.
MEMORY LOST
Occurs when memory is
cleared.
NO SOLUTION - CHECK
INPUT
Occurs when computation
based on input data is not
possible.
ILLEGALENTRY
Occurs when operator tries
to enter data which are not
within input parameters.
WARNING: DATE <1950
Occurs when the operator
tries to enter a pre-1950
date.
SET#1 AZ
SET #2 AZ
SET #3 AZ
Occurs in artillery astro
program when rejection
criteria are not met These
three messages follow the
prompt REJECTION CRIT
NOT MET
LAT NOT WITHIN UTM
Occurs when the operator
tries to enter a latitude
greeter than 84° (north) or
less than -80° (south).
12-7
FM 6-2
e. Program 5–Altitude Method. This program computes
a grid azimuth from three sets of observations of the sun or
a survey star. The program contains two separate
computations–one for sun and one for stars. Computation
of the sun altitude is recorded on DA Form 5594-R.
Computation of star altitude method is recorded on DA
Form 5595-R. Azimuth from three sets of observations are
computed, and the azimuth of each set is compared to the
mean of the three sets. If one of the three sets does not
meet the rejection criteria, the computer will display SET
#_REJECTED. The computer will then calculate a mean
azimuth from the two remaining sets. Should two sets fail
to meet accuracy specifications, the display will be REJECT
CRIT NOT MET. In this case, check the input data and
recompute. If rejection criteria still arc not met, determine
new field data.
CAUTION
Once the user has obtained the final grid azimuth
and it is shown in the GRID AZ/MK display, the backup
function cannot be used, To review any previously
entered data, the operator must use the top of file
function (press T and END LINE keys). The backup
function can be used at any time before the final grid
azimuth is shown in the GRID AZ/MK display.
are recorded on DA Form 5598-R. This program checks
the accuracy specifications in the same manner as Program
5.
i. Program 9—Grid Convergence. This program computes
a UTM grid azimuth from a gyroscopic (true) azimuth.
Computations are recorded on DA Form 5599-R.
j. Program 10—Conversion and Transformation. This
program has three separate operations which are
described below.
(1) Geographic to UTM. This operation computes
conversion of geographic coordinates to UTM coordinates.
Computations are recorded on DA Form 5600-R. This
operation requires the following data:
Ž Spheroid.
Ž Latitude of station.
Ž Longitude of station.
Ž Grid zone.
(2) UTM to geographic. This operation computes
conversion of UTM coordinates to geographic coordinates.
Computation are recorded on DA Form 5601-R. This
operation requires the following data:
Ž Spheroid.
f. Program 6—Hasty Astronomic Observation (Hasty
Astro). This program computes a grid azimuth and check
angle from observations of the sun or a survey star. Data
for either operation are recorded on DA Form 7286-R. The
accuracy of the computation depends on the instrument used
to perform the observation (0.3 roils for the T16). The
program uses the electronic ephemeris, which eliminates the
need to extract data from FM 6-300. The program provides
the option of using the internal timer to determine date and
time of observation or manually inputting dale and time.
The ability to manually input date and time of observation
allows the surveyor to perform fieldwork without BUCS being
at the site of observation.
g. Program 7—Star 11). This program computes the
approximate azimuth and altitude to a selected star at a date
and time chosen by the user. The orientation data will help
identify survey stars for astro observation or navigation. The
program will compute the approximate azimuth and altitude
(vertical angle) to any of the 73 survey stars listed in FM
6-300. The orientation data are accurate to 5.0 roils. Data
for Star ID are recorded on DA Form 7284-R. The form
has space for six sets of data.
h. Program 8—Polaris Tabular Method. This program
computes a grid azimuth from three sets of observations of
Polaris by using the Polaris tabular method. Computations
12-8
Ž UTM casting.
Ž UTM northing.
Ž Grid zone.
(3) Zone to zone. This operation transforms UTM grid
coordinates and grid azimuth from one grid zone to an adjacent
grid zone. Computations are recorded on DA Form 5602-R.
The operation requires the following data:
Ž Spheroid.
Ž Starting grid zone.
Ž Ending grid zone.
Ž UTM casting.
Ž UTM northing.
Ž UTM grid azimuth.
k. Program 11–Trig Traverse and Subtense. This
program has two separate operations-trig traverse and
subtense. Both operations of this program compute
horizontal distances. Computations for both operations
are recorded on DA Form 5603-R.
1. Program 12—Intersection. This program computes the
UTM coordinates of a target by intersection. Computations
FM 6-2
are recorded on DA Form 5604-R. A maximum of 40 targets
can be computed when the same OPs are common to
subsequent targets. This program can be used for either
type of target area base. (intervisible or nonintervisible). The
following data are required:
Ž Coordinates of OP 1 (01).
Ž Coordinates of OP 2 (02).
Ž Azimuth from OP 1 to target.
turns the computer off after 10 minutes of inactivity. The
BUCS has a continuous memory which allows the operator
to recall the last program and its calculations at any time
without loss of survey data.
(1) The operator uses the following steps to recall
the last program and its calculations before the computer
is turned off:
Step 1. Turn the computer on.
Step 2. Press the f key.
Ž Azimuth from OP 2 to target.
Step 3. Press the CONT key.
Ž Vertical angle from OP 1 to target.
Step 4. Press the END LINE key.
m. Program 13–Artillery Astronomic Observation (Arty
Ash). This program computes a grid azimuth from three
observations of the sun or survey star. Data for either
observation is recorded on DA Form 7285-R. This program
uses an electronic ephemeris, which eliminates the need to
extract data from FM 6-300. The program provides the option
of using the internal timer or manually entering the date
and time of tip for each observation. The ability to manually
input the date and time of observation allows surveyors to
perform fieldwork without BUCS being at the site of
observation. The program cheeks the accuracy specifications
in the same manner as Program 5.
12-7. SPECIAL APPLICATIONS
Several special applications of the BUCS can be performed
by the user. These applications are as follows:
Ž Using the continuous memory.
(2) This procedure will recall the program and the
calculations. The computer will display the prompt which
follows the prompt at which the computer turned itself off.
Use the backup procedure to verify the data of the previous
display prompt, and continue computations.
b. Exiting and Reentering BUCS Program Mode. The
BUCS allows the operator to exit the survey program at
any time for the purpose of performing mathematical
calculations independent of the program. The operator
may reenter the survey program at any time without loss
of memory.
(1) The following steps must be performed to exit
the program mode and go to the calculation mode:
Step 1. Press the ON key to clear the display.
Step 2. Press the f key.
Step 3. Press the CALC key.
Ž Setting the time and date.
The computer is now in the CALC mode and ready to
perform mathematical problems independent from the
survey program.
Ž Making time corrections and adjustments
(internal timer).
(2) The following steps must be performed to reenter
the program mode:
Ž Exiting and reentering the program mode.
Ž Determining time accuracy requirements.
Step 1. Press the f key.
Ž Adjusting the contrast of the display.
Step 2. Press the CALC key.
Step 3. Press the f key.
Ž Increasing the speed of data input and
calculations.
Step 4. Press the CONT key.
Ž Clearing the memory.
Step 5. Press the END LINE key.
Ž Inserting RUNNING CLOCK program into
BUCS memory.
a. Using BUCS Continuous Memory. To protect the BUCS
from running down the batteries, a built-in safety feature
The computer will return to the display prompt which
follows the display prompt where the program was exited.
(3) The following steps must be performed to reenter
the program mode at the very start of the display prompt
^DATE 01-JAN-00:
12-9
FM 6-2
TIME: hh:mm:ss. The hh is the hour (24 hour
clock); mm the minute; and SS, the second.
The operator can either accept the displayed
time by pressing the END LINE key or change
it by typing in a new one. If the operator
decides to change the time given, he must
input the entire time, including the seconds.
Step 1. Press the f key.
Step 2. Press the CALC key.
Step 3. Press the RUN key.
Step 4. Press the END LINE key.
The computer is now in the program mode and ready to
perform survey programs 1 through 13.
Note. The procedure in (3) will discard the program
which was run before this procedure.
c. Setting Date and Time (Internal Timer). The BUCS
contains an accurate quartz-crystal clock and a calendar
covering several thousand years. The clock and calendar
are referred to as the internal timer in this chapter. The
internal timer is accessed at the TIME MODULE prompt
in the program instructions. This internal timer runs whether
the BUCS is on or off. It begins as soon as the batteries
are installed. The steps for setting the date and time are
as follows:
Step 1. Turn BUCS on.
Step 2. Type RUN SURVEY.
Ž The SURVEY routine will call a subroutine
(DATIME) which will then request the
date
proper
displaying
by
^DATE:DD:-MMM-YY. The DD is the day;
MMM, the month; and YY the year. The
operator can either accept the date that is
displayed by pressing the END LINE key or
type in a new date in the same format as
given in the prompt and then pressing the
END LINE key.
Ž The subroutine DATIME will next request
the proper time of day by displaying
12-10
The example below shows this procedure.
d. Making Time Corrections and Adjustments (Internal
Timer). BUCS has a versatile set of statements and functions
to set and adjust the quartz-controlled clock and to change
its speed. The system clock is regulated by a quartz crystal
with a typical accuracy of 1.5 minutes per month. The
accuracy of the clock is affected by temperature, physical
shock, humidity, and aging. HP71 Owner’s Manual (Section
5, page 90) describes how to refine the time keeping accuracy
of the clock if required. The time adjustment statements
described in Section 5 must be followed exactly. An improper
use of these statements could lead to a very inaccurate clock
speed.
e. Determining Time Accuracy Requirements. The new
astro programs within the SURVEY MODULE REV1 (Star
ID, Hasty Astro, and Arty Astro) use the hour-angle formulas
to compute azimuth. The new astro programs require the
time accuracies shown in Table 12-7.
Table 12-7. Time accuracies for astro programs
CELESTIAL BODY
ACCURACY OF TIME
Sun
1 second
Stars (other than Polaris)
1 second
Polaris
10 seconds
FM 6-2
f. Adjusting the Contrast of Display.
(1) The BUCS allows you to adjust the contrast by
controlling the display intensity and optimum viewing angle.
You may choose a contrast value from 0 to 15. Contrast
0 gives you the least contrast and shallowest viewing angle.
Contrast 15 gives you the sharpest contrast and steepest
viewing angle and also makes all the annunciators easily
visible. After memory reset, contrast value is set to 9. You
can adjust the contrast value to suit your own preference.
(2) To adjust the contrast and the viewing angle, type
CONTRAST 15 and press the END LINE key. This will
give you the sharpest contrast. Choose your own preference
by selecting any number from 0 to 15.
Note. If the contrast is set to 0, the display appears
blank unless it is viewed at a low angle. Therefore,
when BUCS is turned on with the contrast set to 0,
the BUCS may appear to be off. This problem can
be remedied by setting the contrast to 8.
g. Increasing Speed of Data Input and Calculations.
The BUCS allows the operator to increase the
speed of data input and calculations. This feature
has the advantage of being able to type in
the data without waiting for the next display
prompt.
The disadvantage is that the operator
cannot verify the data until the program is completed.
When using this rapid application, the operator
must have the program prompts completely memorized.
(1) To activate the rapid application type DELAY 0,0
and press the END LINE key.
(2) To deactivate the rapid application, type DELAY
.1,.1 and press the END LINE key.
h. Clearing BUCS Memory. When the SURVEY
REV1 module is installed, BUCS has a 64K
memory and is able to store many programs
of CALC mode and BASIC mode.
However,
when your unit begins field operation, you should
clear the computer memory if it is cluttered
with your personal program. Having the computer
memory filled with your own programs could
result in the BUCS not accepting the survey
programs and prompting INSUFFICIENT MEMORY.
Should this occur, you must clear and reset
the BUCS memory.
To clear and reset the
BUCS main user memory (also called RAM),
the operator must perform the steps discussed
below.
Step 1. Press and release the ON and / keys at the
same time.
Step 2. The display prompts INIT: 1. All the keys
are now inactive except 1, 2, 3, and END LINE.
To reset the memory, press the 3 and END
LINE keys.
Step 3. The display prompts MEMORY LOST. Clear
the display ‘by pressing the ON key.
i. Inserting RUNNING CLOCK Program Into BUCS
Memory.
WARNING
This routine may be used only with the BUCS
SURVEY REV 1 module. Use with any other
module (for example, cannon) is not authorized
because of memory restrictions.
(1) The following program can be inserted into the BUCS
memory to create a RUNNING CLOCK routine:
Step 1. Press the ON key.
Step 2. Type in EDIT CL, and press the END LINE
key.
Step 3. Type in 5 DELAY 0,0, and press the END
LINE key.
Step 4. Type in 10 TIME $, and press the END LINE
key.
Step 5. Type in 20 GOTO 10, and press the END
LINE key.
This routine will now remain in your BUCS indefinitely
unless BUCS power has been lost for more than 30 seconds.
If the program is lost, it can be reinserted again following
the procedure in (1) above. If you make a mistake while
inserting the program into BUCS memory, press the ON
key and start again with step 1.
(2) To check the accuracy of your BUCS clock once
the RUNNING CLOCK routine has been inserted into the
BUCS memory, perform the following:
Step 1. Press the ON key.
Step 2. Type in RUN CL, and press the END LINE
key.
12-11
FM 8-2
BUCS will now display a running clock. The displayed
time should be checked against a time signal received via
a time signal receiver. BUCS displayed time may be about
1/2 second behind the actual time. This discrepancy is due
to the inserted RUNNING CLOCK routine and should not
be construed as an error in the time setting. Once the BUCS
clock has been viewed long enough to ascertain i fit is correct,
press the ON key to stop the clock. If the time is correct,
key in RUN SURVEY to start your survey computations.
If the time is not accurate enough to compute astro
observations (hasty astro or arty astro) by using the BUCS
internal clock, key in RUN SURVEY and set the correct
time into the BUCS internal clock at step 2 (TlME prompt).
To recheck your BUCS clock, press the ON key and perform
steps 1 and 2 above.
12-8. MAINTENANCE AND
TROUBLESHOOTING
a. Computer and Printer Maintenance The HP71B
computer and HP2225B printer can be cleaned with a soft
cloth, dampened either in clean water or in water containing
a mild detergent. Do not use an excessive y wet cloth or
allow water to get inside these components. Do not use
abrasive cleaners on the computer display window. The
printer battery pack is not use-serviceable.
WARNING
Do not incinerate or mutilate the printer battery
pack. The battery pack may release toxic
materials or burst under extreme heat. Do not
connect together or otherwise short-circuit the
battery pack terminals. The battery pack may
melt or cause serious burns.
b. Print Head Maintenance. The HP2225B print head
cartridge is easy to maintain. Avoid touching the print head
face with your fingers. Avoid allowing the print head face
to come into prolonged contact with other materials. This
may cause the ink to wick out of the print head.
WARNING
The ink in the print head cartridge contains
diethylene glycol, which is harmful if swallowed.
c. Troubleshooting. Table 12-8 lists the possible error
conditions that may occur on the ThinkJet printer and the
corrective action for eliminating the problem.
12-12
FM 6-2
Table 12-8. Troubleshooting
ERROR CONDITlONS
CORRECTIVE ACTIONS
1. Red power light is off or flashing.
Ensure battery pack is installed correctly and POWER switch is turned on. If
power light remains off or is blinking, the battery pack should be recharged.
2. Yellow attention light is on continuously.
Load paper into printer. Attention light will start blinking.
3. Yellow attention light is blinking.
Press blue button. Print head cartridge will move, and attention light will go out.
Remove any obstruction from around print head cartridge, and push blue button
again. If attention light continues blinking, printer is signaling an error condition
and should be turned in for repair.
4. Printer does not respond to computer.
Make sure that power light is on or blinking and attention light is off. If this is not
the case, refer to error conditions 1 through 3 above. Verify that printer is
operational by running the self-test (Chapter 1 of HP71B Owner’s Manual). Verify
that the HP-IL cables are property connected, and repeat the procedure for
assigning printer as system print device. This procedure is explained for several
different HP systems in appendixes of HP2225B Reference Manual. You may also
need to refer to HP71B Owner’s Manual. Computer may not be sending printer a
carriage return and line feed at end of each line. In this case, printer will continue
storing data because it never recognizes end of the line. Refer to automatic line
termination on page 3-7 of the HP2225B Reference Manual and to the HP71B
Owner’s Manual for the reset procedures.
5. Paper does not feed properly.
Remove paper from printer, and discard any that is crumpled. If using fanfold
paper, verify that it can travel freely without catching and that right side pinwheel is
adjusted correctly for width of paper. Reload paper according to instructions in
Chapter 1 of the HP2225B Reference Manual.
6. Print quality is poor, dot rows are missing, Ensure there is sufficient ink in cartridge by viewing the ink bladder. If bladder is
and carriage moves but printer does not print. collapsed, replace cartridge. Using a tissue, gently wipe face of print head to
remove any accumulated dust if print head cartridge has not been used for
several days, moisten tissue with water before wiping. Using a cotton swab
dipped in alcohol, lightly wipe electrical connector of print head cartridge, if
problem continues, replace print head cartridge.
12-13
C1, FM 6-2
Chapter 13
SATELLITE SIGNALS NAVIGATION SET AN/PSN-11
The satellite signals navigation set AN/PSN-11 (NSN 5825-01-374-6643)
will provide worldwide position, velocity, and time to the field artillery
surveyor. When survey control is not available and time or the tactical
situation preclude the use of existing survey control, the surveyor can use
the AN/PSN-11 to establish positioning data.
The AN/PSN-11 (Figure 13-1) is a receiver. It is used in the global
positioning system (GPS), standard positioning system (SPS), and precise
positioning system (PPS).
position and velocity information, and time. The GPS is
comprised of three major segments as depicted in Figure
13-2.
Figure 13-2. Global positioning system
Figure 13-1. AN/PSN-11
13-1. GLOBAL POSITIONING SYSTEM
The NAVSTAR GPS is a space-based navigation and
positioning system that provides accurate, three-dimensional
a. The space segment is made up of a 24-satellite
constellation that orbits the earth once every 12 hours.
These satellites are deployed in six orbital planes and are
configured so that four or more satellites will be in view
at all times. This arrangement allows for 24-hour,
three-dimensional, worldwide coverage. As with the stars,
the satellites rise above the horizon about 4 minutes earlier
than the previous day.
13-1
C1, FM 6-2
b. The control segment consists of five passive-tracking
monitoring stations, active-tracking ground antennas, and the
master control station located at Falcon Air Force Base,
Colorado. These tracking stations, located around the world,
are capable of monitoring the satellite navigation messages
and time signals better than 90 percent of the time. This
information is relayed to the master control station, which
has the capability to effect any needed corrections to the
satellite timing and navigation messages.
c. The user segment consists of navigation receivers
designed for marine, aircraft, and manpack or vehicle use.
The receivers must have electrical line-of-site with the
satellites to receive and decode the satellite signals. The
internal computer uses these satellite data to generate a precise
time, velocity, and three-dimensional (3D) position data. The
receiver must track four satellites to obtain a 3D position,
and three satellites will yield a two-dimensional (2D) position.
Current position coordinates and height are obtained from
a 3D position and only current coordinates are obtained from
a 2D position. The receiver needs only one satellite for
precise time.
13-2. STANDARD POSITIONING SYSTEM
AND PRECISE POSITIONING SYSTEM
a. The SPS is available to all GPS receivers worldwide,
both military and civilian. When a receiver is in the SPS
mode, almanac, navigation, and timing information are
received on the nonencrypted course acquisition (CA) code
satellite signal. To deny unauthorized users the full accuracy
of GPS, the Department of Defense (DoD) intentionally
places errors in the navigation and timing signal. This process
is called selective availability (SA). The SA errors are
unpredictable and can produce significant horizontal and
elevation errors. This is one reason why SPS receivers are
not authorized for combat operations.
b. The satellites also broadcast an encrypted precise (P/Y)
code. This transmission is the basis for the PPS that is
used by military GPS receivers. These receivers must have
crypto keys loaded to detect and nullify the SA errors, which
allows for more accurate position data. Also, the crypto
keys provide a means of unscrambling the encrypted P/Y
code, which is an antispoofing (AS) protection. Receivers
such as the AN/PSN-11 have this capability and are
considered to be PPS receivers. Only PPS receivers are
authorized for combat operations.
13-3. FA SURVEY APPLICATION
a. The current AN/PSN-l1 basis of issue plan (BOIP) calls
for one receiver with each PADS team, each conventional
survey team or party, and the survey headquarters or SPCE.
b. Field artillery survey personnel will primarily use the
AN/PSN-11 to initiate surveys when existing survey control
is not available. This receiver allows the surveyor to begin
surveying immediately with more accuracy than assumed
data or a map spot.
c. A description of all parts, components, and detailed
operating procedures for the AN/PSN-11 can be found in
TM 11-5825-291-13. All operators should be thoroughly
trained on all functions of the system before using the
AN/PSN-11. The general how-to procedures for operating
the AN/PSN-l1 will not be in this manual. Only those
issues that deal with survey positioning and orientation or
specific recommended procedures will be addressed.
(1) Setup. The setup selections allow the AN/PSN-11
operator to select several options and modes of operation.
(See TM 11-5825 -291-13.) An example of a typical setup
for artillery surveyors is shown in Table 13-1.
Table 13-1. Example AN/PSN-11 setup
13-2
C1, FM 6-2
Table 13-1. Example AN/PSN-11 setup (Continued)
(2) Position. Whenever coordinates are being determined
for a critical position such as an orienting station, howitzer
location, and PADS initialization or update point, use extreme
care. To meet required accuracy, the system must have
crypto keys loaded, be set on the correct datum, and indicate
a FOM 1 before the coordinates will be used. The
AN/PSN-11 with a FOM 1 will meet or exceed an accuracy
of 10 meters CEP for horizontal and 10 meters PE for
vertical. The averaging mode will yield a more stable and
accurate set of coordinates. After the set attains FOM 1,
switch to the averaging mode, and allow the counter to
increment to at least 300 counts. (This will take about 5
minutes.) Position data should always be checked by a
second independent mean; for example, a second receiver,
an accurate map spot, or the current coordinates on the PADS.
(3) Height. The AN/PSN-11 can determine height
(elevation) relative to either the horizontal datum ellipsoid
(spheroid) or mean sea level. Both modes of operation can be
set for meters or feet as a unit of measurement. Normally,
mean sea level and meters will be the preferred selections.
(4) Direction. The AN/PSN-11 should never be used to
determine orientation azimuth for firing positions. As with
the PADS, azimuth computed between two sets of GPS
coordinates will produce erratic results.
(5) PADS operation. The AN/PSN-11 does not require
any special installation for PADS operation. Position
coordinates for initialization or update can be obtained by
moving a short distance away from the vehicle and placing
the set directly over the desired location. Using the system
away from the vehicle will reduce the possibility of antenna
masking. When the averaged FOM 1 coordinates have been
recorded, move the PADS vehicle to the AN/PSN-11 position.
If the AN/PSN-11 auxiliary antenna is mounted on the
vehicle, the precise GPS vehicle lever arms information (X,
Y, Z) must be entered during system initialization as outlined
in TM 5-6675-308-12 with Change 3. The operating
13-3
C1, FM 6-2
instructions in the current PADS TM (Chapter 3, in Change
3) applies to older GPS receivers. When using the
AN/PSN-11 during PADS operations, only data determined
from a FOM 1 will be used.
13-4. GPS LIMITATIONS AND
CONSIDERATIONS
a. Masking. GPS receivers rely on electronic line of sight
with the satellites. Therefore, dense foliage, buildings,
mountains, and canyons may mask the signl. The
AN/PSN-11 will initially select satellites that are 10° or
more above the true horizon. If for usable satellites are
not detected, the set will switch to 0° until satellite acquisition.
After acquisition, the set will switch to 5° above the horizon
for normal operation. If enough satellites cannot be acquired,
the receiver must be moved to a more suitable location.
b. Jamming. The AN/PSN-11 is subject to jamming.
When low signal to noise ratios are detected or reception
is blicked altogether, jamming may be the cause. Move to
a new location, and try to place something between the
receiver and the suspected jammer. When the signal to noise
ration is above 34 decibels (db), jamming has probably been
eliminated.
13-4
c. Spoofing. The AN/PSN-11 may be subject to spoofing
errors. These errors are caused by false satellite signals
designed to generate errors in navigation and position data.
Maximum protection against spoofing is attained by using
the crypto keys and the All-Y setup selection. If the
AN/PSN-11 is in a spoofing environment, the system may
sense spoofer activity and generate a POSSIBLE SPOOFERS
warning screen.
d. Temperature. The AN/PSN-11 operating range is -4
to +158° F. When operating in cold regins, protect the
receiver by carrying it inside your outer clothing or operating
it from a heated vehicle. This can be done by using the
auxiliary antenna.
e. Power. The AN/PSN-11 will normally be operated by
using either a BA5800/U lithium battery or 24-volt vehicle
power. Operating in the continuouts mode, the battery will
provide adequate power for about 15 hours at 71° F. During
extended missions, spare batteries must be readily available.
Using vehicle power eliminates this problem; however, the
correct polarity must be observed to prevent damage to the
system.
C1, FM 6-2
CHAPTER 14
SURVEY OPERATIONS
To support current Army doctrine, survey operations must be responsive,
accurate, and flexible. The artillery surveyor's primary mission is to provide
accurate orientation and determine the coordinates and height of weapons
and target-locating systems relative to one another. This is known as
establishing a common grid. The task of providing a common grid involves
different levels of command and echelons of survey. Beginning at the echelon
above corps, topo surveyors establish third-order or higher SCPs in the corps
and EAC areas for Patriot, corps general support units, and other units.
Topographic surveyors also provide SCPs in the division area for the div arty
surveyors. Div arty and TAB surveyors extend control to battalion areas,
where the battalion surveyors extend control to the weapons and target-locating
devices. This chapter discusses the survey operations typical of the following:
Common grid.
Cannon battalion.
Missile and rocket battalions.
Division artillery.
Target acquisition battery and detachment.
SPCE (corps and brigade).
Special environments.
Section I
CANNON BATTALION SURVEY
The primary mission of the surveyors in a cannon battalion is to provide timely and accurate
survey control to the firing batteries and any other battalion assets as required. Survey control
consists mainly of establishing a line of known direction and determining the locations, both
horizontally and vertically, of the weapons and the target-locating systems. In addition, FA battalion
survey must provide control for other weapons, instruments, and electronic equipment as required.
14-1. REASONS FOR COMMON GRID
Accomplishment of the battalion survey mission provides
a common grid for firing units and target-locating systems
within prescribed accuracies. A common grid allows the
cannon battalion to do the procedures below.
a. Mass Fires. Accurate survey permits rapid and
economical massing of fires. For artillery to mass fires
accurately without survey requires an observed adjustment
of all units on the target or prior registration of all units on
a common registration point.
b. Deliver Surprise Observed Fires. If survey is not
available and all batteries are required to adjust on a target,
the element of surprise is lost. Complete surprise is
impossible without survey.
c. Deliver Effective Unobserved Fires. Without survey,
consistently effective unobserved fires are possible only if
the target has been fired on previously and replot data have
been computed.
d. Transfer Target Data Between Units. Transfer of target
data between units is possible only when units are located
relative to each other and to the target (on a common grid).
14-1
C1, FM 6-2
Known coordinates, height, and azimuth.
should approximate the correct grid azimuth as closely as
possible. The approximate grid azimuth can be determined
by using a compass (preferably declinated) or scaling from
a large-scale map. If either a higher or lower survey echelon
or both initiate survey operations with assumed azimuths,
differences of varying magnitude will exist between the
coordinates of points located by their surveys (Figure 14-1).
This variation complicates the problem of conversion to
common control. For this reason, an assumed azimuth should
never be used if the correct azimuth can be determined.
.Assumed coordinates and height and correct grid azimuth.
14-3. CONVERSION TO COMMON GRID
14-2. VARIATIONS IN
STARTING CONTROL
Starting control for FA survey consists of the coordinates
and height of a survey control point and a starting azimuth.
Although there are several ways in which starting control
can be obtained, the best control available for the area should
be used to begin a survey. The variations of starting control
can be grouped into three general categories as follows:
Known or assumed coordinates, height, and azimuth.
a. Known Coordinates, Height, and Azimuth. Starting
control for which the station data are known may be points
established by survey done by a higher echelon, or it may
be confirmed data established before the start of military
operations. Data for stations established by engineer topo
units and data for survey control established before the start
of military operations are in trig lists prepared and published
by the DMA. Survey data for survey stations established
by div arty are published in trig lists prepared in the div
arty SPCE and distributed to all using units in the area.
(1) If the PADS is to use starting control established
by conventional survey methods, the SCPs at both ends of
a PADS survey must be on a common grid.
(2) If conventional survey starts from a point
established by the PADS or GPS, the survey must close on
that same point.
b. Assumed Coordinates and Height and Correct Grid
Azimuth. When survey control is not available in the area,
the coordinates and height of the starting station must be
assumed. Correct grid azimuth can be determined through
astronomic observation, an azimuth gyro, or the PADS.
Correct grid azimuth should always be used whenever
possible. If both higher and lower survey echelons initiate
surveys by using correct grid azimuths, any discrepancy
between surveys that is due to assumption of coordinates
will be constant for all points located (Figure 14-1). The
approximate coordinates and height of the starting point can
be determined from a large-scale map and should closely
approximate the correct coordinates and height to facilitate
operations. Starting data determined from a map must always
be considered as assumed data. A survey starting on an
assumed point must close on that same point.
C.
Known or Assumed Coordinates, Height, and
Assumed Azimuth. Assumed azimuth should be used for
a starting azimuth only when azimuth cannot be determined
from astronomic observations, an azimuth gyro, the PADS,
computation, or a published trig list. The assumed azimuth
14-2
a. A battalion SCP is a point provided by a higher survey
echelon for the purpose of initiating survey control for the
battalion. More than one of these points may be required
for a battalion. SCPs on the grid of the next higher echelon
may be available in the form of one or more trig points in
the vicinity of the battalion installations. When available,
trig points from DMA or other published trig lists should
be used as the basis for all echelons of survey operations.
When one or more SCPs have been established by the next
higher echelon, these SCPs should be used as the basis for
battalion survey operations. In either situation, the common
grid is established.
b. The mission of the subordinate unit requires it to
initiate survey operations without waiting for survey
control to be established by a higher echelon. Thus, a
battalion assigned or attached to a div arty may have to
operate first on the grid established by the battalion
(battalion grid) and finally on the grid established by corps
(corps grid). When survey at one or more echelons is
based on assumed data, data established by the lower
echelon should be converted to the grid established by
the higher echelon. An exception to this rule would be
when prescribed accuracies are met or when the tactical
situation, time constraints, or SOP causes the commander
to decide otherwise.
c. When both higher and lower survey echelons start
PADS or conventional survey operations with correct grid
azimuth but one or both of them start with assumed
coordinates and height, the lower echelon must apply
coordinate and height corrections to the location of each
critical point in its survey to convert to the grid of the
higher echelon. This coordinate and height conversion
is commonly known as sliding the grid (Figure 14-2) and
is done as follows:
(1) Determine the differences in casting coordinates,
northing coordinates, and height between the assumed starting
point and the common grid starting point provided by the
higher echelon. The difference, with its appropriate sign,
becomes the correction. (See the example below.)
C1, FM 6-2
Figure 14-1. Discrepancies in survey control caused by use of assumed starting data
FIGURE 14-2. Sliding the grid.
14-3
C1, FM 6-2
(2) Apply the corrections (differences) to the assumed
data to make the assumed data equal the common grid data
(coordinates and height) at all critical points.
must recompute the entire survey again. This is done by entering
the correct (common) starting data and all field data and by
following normal computational procedures.
d. Whenever survey operations are started with an
assumed azimuth, regardless of whether the coordinates
and height are known or assumed, the coordinates of
each station and the azimuths determined will be in error.
To convert the assumed data to correct grid data, all
azimuths and coordinates determined in the scheme must
be corrected. Application of the azimuth correction
when using known coordinates and height with an
assumed azimuth was referred to as swinging the grid.
When both assumed coordinates and height and azimuth
are used, it is known as swinging and sliding the grid.
With the acquisition of more rapid means of computing
(BUCS and FED MSR), these methods are no longer
required. The procedures for converting assumed
azimuth and/or coordinates to common control are
discussed below.
(1) When using the BUCS to convert assumed azimuth
and/or coordinates to common control, use the following
procedures:
(2) When using the FED MSR, recompute the entire
survey by recalling the survey that needs converting to
common control and exchange the assumed data with the
correct (common) data. Then repeat by pressing the C button
and recording all critical data as they appear.
4
(a) If the survey data that needs converting is still in
the BUCS, recompute the entire survey. This is done by going
to the top of file (T, END LINE) and exchanging the assumed
data with the correct (common) data. Then repeat by pressing
END LINE and recording all critical data as they appear.
(b) If you have started computing another survey or
the survey that needs converting is no longer in the BUCS, you
Note. The FED MSR will hold three computations of
each type of survey. However, if the survey requiring
conversion is no longer in the FED MSR, you must
recompute the entire survey by entering the correct
(common) starting data and all field data and by
following normal computational procedures.
14-4. POSITION AREA SURVEY
REQUIREMENTS
Survey control is required in the position area of each firing
battery of an FA cannon battalion. The HQ battery survey
section using the PADS or a conventional survey team
performs the survey. Position area survey requirements are
identical for light, medium, and heavy artillery batteries.
(See Figure 14-3.) If the battery is using the split-battery
concept of operations, survey control is provided for each
firing platoon. (See Figure 14-4.) Requirements for position
area survey are described in paragraphs a through g on the
next two pages.
Figure 14-3. Conventional position area survey
14-4
C1, FM 6-2
Figure 14-4. Split-battery position area survey
a. Battalion and Battery Survey Control Points. As
mentioned earlier, survey control for artillery units may be
available in the form of SCPs established by higher echelons
or trig lists containing data for stations located near the unit.
The locations of SCPs established by div arty must allow
for the survey capability of the battalion. An SCP must be
provided within 5 km of the center of the battalion position
area if the PADS is the primary method of survey. When
the battalion is limited to conventional survey methods, div
arty survey must provide SCPs within 2,000 meters of the
firing positions. If the firing elements are widely dispersed
or operating separately, it may be necessary to establish
more than one SCP. If there are no SCPs in the battalion
area, the battalion RSO will select a convenient point near
a prominent terrain feature and assume starting control. The
div arty survey officer (survey platoon leader) may task direct
support (DS) battalions to provide survey control for
supporting units located in the battalion area of operations.
b. Firing Battery Positions. Survey requirements in each
firing battery position are described in (1) through (3) below.
(1) Orienting station. The OS is a station used by the
firing battery or platoon personnel to orient the weapons.
The coordinates and height of the OS and a line of known
direction are required. The position of the OS is usually
selected by the battery commander or executive officer (XO),
but it can be selected by the survey personnel. The frequent
moves and the many positions required will not always allow
the battery commander and/or XO to select all 0Ss. The
relative locations of the OS and EOL usually are addressed
in the unit survey SOP.
(2) End of the orienting line. The EOL is a survey station
used as an azimuth mark for the OS. The EOL must be
located so that it is visible and at least 100 meters from the
OS.
(3) Orienting line. An OL is a line of known direction
materialized on the ground in each position area. It is used
as a reference direction for orienting instruments and for
laying weapons for direction. When the PADS is used to
establish the OL, the two-position mark is the preferred
method. If autoreflection is used, a one-position angle must
be measured. When the OL is established by conventional
survey, it should be a main scheme leg to ensure accuracy.
c. Field Artillery Radar Locations. One weapons-locating
radar (WLR) section (AN/TPQ-36) normally is attached to
each DS howitzer battalion. The coordinates and the height
of the radar position (near stake) and a line of known direction
to an azimuth mark (far stake) are required. The distance
and vertical angle to an azimuth mark are also required.
The battalion survey section is responsible for determining
these data. Usually, the WLR (AN/TPQ-37) will be located
near one of the artillery battalions. Div arty may task the
nearest battalion to provide survey control. The radars
require coordinates and height of the radar position and
distance and direction to an azimuth mark. (See Figure
14-5.) The PADS is the primary means of obtaining survey
control for the Firefinder radars (AN/TPQ-36 and
AN/TPQ-37). When the PADS is not available before the
14-5
C1, FM 6-2
radar section occupies the radar site, fifth-order survey will
be provided by a conventional survey team or the radar
section will conduct a hasty survey. The hasty survey will
provide the data for initializing the radar. If the PADS or
conventional survey team arrives after the hasty survey has
been completed, the data determined by the PADS or
conventional survey will be entered into the radar computer
instead of the hasty survey data. Azimuth required by the
Firefinder radars must be accurate within 0.4 mil. The
position accuracy required is 10 meters. The vertical interval
accuracy is 10 meters for the AN/TPQ-36 and 3 meters for
the AN/TPQ-37. However, the weapon location accuracy
of the AN/TPQ-36 is greatly enhanced by keeping the vertical
interval accuracy within 3 meters. This accuracy is within
the capabilities of the PADS and fifth-order survey.
d. Declination stations. A declination station should be
established at a place that is convenient to using units. It
may be established by an FA battalion, a div arty, or a
TAB. The ideal declination station should have known grid
azimuhs to four prominent features (for example, a church
steeple, radio towers, quad markers). Preferably there should
be one prominent feature in each quadrant and at least 1,000
meters from the declination station. When time, tactical
situation or lack of prominent features limit operations,
azimuth marks can be established (for example, range pole).
However, a minimum distance of 300 meters should be used
if possible.
(1) In establishing a declination station, the direction of
each azimuth mark may be determined by computing the
azimuth (if the coordinates of the declination station and
azimuth marks are known), by applying a measured angle
to a known direction, by astro observations, or by using
PADS with optical transfer. The theodolite is used in
measuring angles or making astro observations to determine
the azimuths for the declination station.
Railroad tracks, artillery, tanks, and vehicles: 75
meters.
Barbwire and personal weapons: 10 meters.
(3) Whenever a declination station is established, the
vertical angle to each azimuth mark should be determined.
The vertical angle correction for the aiming circle can then
be determined at the same time it is being declinated.
(4) Any SCP with an azimuth mark may be used as a
declination station if the area is free from local magnetic
attraction.
e. Intelligence Electronic Warfare Sites. When IEW sites
are established in the battalion area, the div arty survey
officer may task the battalion survey section to provide survey
control.
f. Meteorological Sites. Met sites usually do not require
survey control. A map spot and the met section declinated
theodolite usually are accurate enough. However, when the
map accuracy is doubtful or maps of the area are not available,
the nearest artillery battalion may be tasked to provide survey
control.
g. Alternate, Supplementary, and Offset Registration
Positions. Survey of alternate, supplementary, and offset
registration positions should be performed as soon as survey
operations for primary positions are completed. Survey
requirements for alternate positions are the same as those
for primary positions.
14-5. CONVENTIONAL METHODS OF
POSITION AREA SURVEY
a. Any conventional survey method or combination of
methods may be used to perform the position area survey.
The method most commonly used is traverse, electronic or
taped. The position area survey starts at an SCP, moves to
(2) Declination stations should be established in an area
its destination, and ends on another SCP (on the same common
free from local magnetic attraction. The following minimum
grid) or the starting point. All surveys should be started
distances from common objects with magnetic attraction are
and closed on an SCP of greater accuracy than the survey
prescribed:
being performed. All position area survey requirements are
Power lines and electronic equipment: 150 meters.
executed to fifth-order accuracy.
Figure 14-5. Radar survey
14-6
C1, FM 6-2
b. When a firing battery or platoon position is surveyed,
an OS is established from which all weapons will be visible.
This point is used as one EOL, and the traverse leg used
to establish the station is used as the OL. This makes the
OL a leg of the closed traverse and thus permits the detection
of any error in the OL should the traverse not close in azimuth,
The OL should be checked by using a compass. Marking
of the OS and EOL is established by unit SOP.
14-6. CONNECTION AREA SURVEY
a. Connection area survey, when required, is that part of
the survey operation performed for the purpose of placing
target area surveys and position area surveys on a common
grid. Surveyors performing the connection area survey may
establish the actual OPs or provide only a target area SCP.
If only a target area SCP is established, then survey control
must be extended to the desired target locators by FA
surveyors during target area survey operations.
b. The connection area survey normally is started from
the battalion SCP and is closed on either the starting point
or any other SCP on the same grid network. When the
PADS is unavailable and time is critical, the connection
area survey may be limited to a directional traverse or
astro observation performed at the OPs. The OP locations
can then be determined by resection or map spot if the
common grid and the grid of the map are the same.
c. Additional requirements in the connection area survey
may include providing survey control for mortars within
the supported brigade and combat electronic warfare and
intelligence (CEWI) target-locating devices located within
the area. The div arty survey officer will designate
priorities. Control is extended to these installations as
provided in the survey plan. Priorities of the FA battalion
requirements must be indicated in an SOP or in the
operation order (OPORD).
effectively mix conventional survey methods with PADS
operations. When target area survey is required, the PADS
crew will establish an SCP with an azimuth mark as close
as possible to the OPs as part of the connection area survey.
The conventional survey team will then perform the target
area survey.
b. Accomplishment of the target area survey mission
requires that a base be established from which the targets
and critical points can be surveyed. The requirements
for establishing a target area base are to locate two or
more OPs relative to each other that overlook the target
area, to determine the azimuth and distance between the
two, and to determine an azimuth to a visible azimuth
mark for each. The OPs are designated 01, 02, and so
forth; and 01 is considered the control OP. 01 may be
on the right or left of the base. However, it is always the
OP requiring the least amount of fieldwork to establish
its location. This is because less directional accuracy is
lost through angular measurements when the number of
main scheme angles is held to a minimum. (For example,
if the OP on the left can be established in two traverse
legs from the target area survey control point [TASCP]
and five traverse legs are required to establish the OP on
the right, then the OP on the left would be designated as
01.) (See Figure 14-5a.)
Figure 14-5a. Target area base
14-7. TARGET AREA SURVEY
a. The need for target area survey performed by the FA
surveyor decreases as new positioning and/or navigational
devices are fielded. As the capability of target locators
to locate themselves and targets increases, the requirements
for target area survey will eventually disappear. Also,
the emplacement of fixed OPs does not complement ALB
doctrine, and the fast-moving battlefield situation will
require the survey effort of the entire survey section to
provide survey control for weapons and target-locating
systems. However, until the target locators are totally
self-sufficient in providing accurate target data and for
environments that favor fixed OP locations (static
situations), the FA surveyor must be able to perform target
area survey. For surveyors, this means being able to
14-7
C1, FM 6-2
14-8. PALADIN SURVEY
a. Paladin Element. The Paladin is an M109A6
self-propelled howitzer equipped with a modular azimuth
positioning system (MAPS). With MAPS, the Paladin has
more flexibility and requires fewer crewmen and less
equipment. The Paladin battery normally operates in a
two-platoon configuration (three howitzers per platoon).
Normally, an M109A2/A3 platoon is allocated a position
area goose egg of about 1,000 meters in diameter. In contrast,
a Paladin platoon requires a position area on the order of
2,000 by 1,000 meters and it uses all of that terrain during
normal operations. Limitations of the on-board navigational
system restrict the howitzer displacement distance. The
Paladin must be updated every 16 miles or 27 kilometers
to ensure it meets position accuracy requirements.
b. Survey Requirments. If the Paladin battalion is to
accomplish its mission effectively, survey operations must
be continuous and carefully coordinated. The battalion S3
and RSO must use their limited survey assets (two PADS
and one conventional team for six platoons) wisely. The
primary responsibility of the PADS teams are to establish
update points along the routes of march and two update
points per platoon position area to ensure that no Paladin
has to travel more than 16 miles/27 kilometers without
updating. If the battalion has set up a rearm, refuel resupply,
and survey point (R3SP), update points should be set up
next to the fuel trucks so the howitzers can perform an update
while refueling. If no R3SP is set up, establish four update
points, spaced 50 to 100 meters apart near the release point
of a tactical road march. These points should be easily
identifiable and accessible without detouring far from the
route of march, and without clogging traffic along the route
of march. This will allow the entire platoon to update at
once, so that they will not hold up the rest of the battalion.
c. Alternative Survey Control. If one or both PADS
become inoperative, the RSO must ensure that the survey
mission continues. The conventional team supplemented
by the inoperative PADS team members must provide update
points. They can use whichever conventional method that
time allows to provide the best available update points
possible until the PADS is operating again. Hasty survey
methods or a PPS GPS receiver can also be used by the
howitzer crew as a last resort.
Section II
MISSILE AND ROCKET BATTALION SURVEY
The survey mission in MLRS and Patriot missile units is to provide timely survey control within
prescibed accuracies. Numerous alternate position areas are essential for survival, and all require
the same survey as the primary position area. Each system has individual requirements that vary
slightly from other FA systems. These differences are due to equipment design, number of launchers,
and auxiliary equipment requiring survey control.
14-9. MLRS SURVEY
8 km traveled to minimize location error. The survey
section must provide update points for the SRP/PDS.
a. MLRS Element. The MLRS is a fully tracked, highly
mobile, rapid-fire, free-flight rocket system that is designed
to complement cannon artillery and supplement other fire
support systems. MLRS battalions are assigned to corps,
and MLRS batteries are organic to armored and
mechanized infantry division artilleries. MLRS batteries
are organized so that each is a relatively self-sufficient
unit. Each MLRS firing battery has three firing platoons
with three launchers per platoon. Each launcher is
equipped with an SRP/PDS, which is an on-board
navigational system. The SRP/PDS provides direction,
elevation, location, and launcher cant angle data to the
fire control system. Once updated at a survey control
point, the SRP/PDS continuously carries accurate location
data that are used by the fire control system to compute
fire missions. The SRP/PDS must be updated every 6 to
b. Survey Requirements. The ability to deliver MLRS
rocket fires accurately and effectively largely depends on
accurate survey information. The battery operations officer
directs and monitors survey operations. The survey chief
is the battery commander’s immediate advisor on all survey
matters. The primary responsibility of the PADS team is
to establish SCPs every 6 to 8 km throughout primary, future,
and alternate locations. Each platoon could occupy from
three to six new positions per day. (See Figure 14-6.)
14-8
(1) SCPs are used to initialize, update, and calibrate the
SRP/PDS aboard the launcher. These SCPs are established
with the PADS by using 10-minute Z-VEL corrections.
Directional control is not required for the MLRS. At least
one SCP must be available in each of the three firing platoon
positions.
C1, FM 6-2
(2) Although cover and concealment are considerations
in platoon area survey point (PASP) selection, utility should
be the primary consideration. The PASP must be readily
accessible so that the driver can stop the launcher next to
the SCP without a ground guide or excessive maneuvering.
(3) In the motor park area, each launcher should have
an individual SCP for initialization. This option will enable
the launcher to leave the motor park area in a HOT status
and be able to accept fire missions immediately.
(4) The launcher crew calibrates the SRP/PDS whenever
the launcher carrier track system is replaced or repaired.
Calibration must also be performed when there is a significant
change in the terrain of the operating area. Two SCPs located
4 to 6 km apart are required for conducting calibration. The
launcher must be calibrated every 30 days, after PDS
maintenance, and after major suspension or track drive
maintenance.
c. Alternative Survey Control. If the PADS becomes
inoperative, the battery commander must ensure that the
survey mission is continued. In this situation, survey control
should be obtained from other FA units operating in the
area or may be established by using a combination of
conventional and hasty survey techniques. The PADS team
can continue the mission by using conventional survey
methods that can be performed by two men with a theodolite
and the BUCS. Battery personnel must help the PADS team
in the survey effort by using the AN/PSN-11 (PLGR) to
establish coordinates at the firing point. For guidance on
the use of the AN/PSN-11, see Chapter 13. When location
data are determined by hasty survey or map reading skills,
the distance traveled by the MLRS between update points
cannot exceed 6 km. The unit must train and rehearse these
techniques at every opportunity, both in the field and in
garrison, to ensure that personnel have the skills needed to
consistently obtain accurate results. It must be understood
that these alternative methods are to be used only in
emergency situations.
Figure 14-6. Typical MLRS firing platoon position area
14-9
C1, FM 6-2
14-10. PATRIOT MISSILE
BATTALION SURVEY
control can be converted to the corps grid when corps
control becomes available.
a. Battalion Survey Elements. The mission of the Patriot
missile battalion requires that the unit be employed, in
most cases, over a very wide frontage and in great depths.
Under the present organization, the battalion consists of
three batteries of six launchers each. Future plans are to
increase the organization to six batteries of eight launchers
each. The battalion HQ battery (one of three battalion
batteries) is authorized three PADS teams. Each PADS
team consists of one E5 and one E3 (MOS 82C). The
six-battery battalion will be authorized four PADS teams.
A survey HQ element and an SPCE are organic to the
HQ battery. The HQ element consists of the chief surveyor
and an E3 driver. The SPCE consists of an E5 and E4.
The chief surveyor, who works directly under the battalion
reconnaissance, selection, and occupation of position
(RSOP) officer does the detailed survey planning and
supervision to ensure that adequate survey control is
available. He also has responsibility to train, supervise,
and coordinate the activities of the PADS teams and SPCE
personnel. The primary mission of the Patriot survey
personnel is to place the firing units and supporting
elements on a common grid. This mission is accomplished
by proper planning, coordination, and organization for
survey by the chief surveyor. The common grid on which
the Patriot battalions operate should be the corps grid. If
corps SCPs are not available within the battalion area,
the chief surveyor must select a known point or assume
survey control and establish his own grid. Control is
then extended from this point to the firing units. This
b. Employment. The Patriot battalion is employed in two
basic configurations. These are the area (belt) defense
(Figure 14-7) and the forward area defense engagement
coverage (Figure 14-8). Figures 14-7 and 14-8 show the
six-battery battalion. Battalions with fewer than six batteries
should modify these defense designs to use available tiring
units effectively.
(1) Area (belt) defense. Patriot battalions are employed
in the area defense to counter enemy attempts to penetrate the
rear operations area to attack deep strike assets. In this type
of employment, the batteries are spread across a front of about
200 km. Because of this wide frontage and the limitations of
the PADS, the topo survey company must provide at least
three SCPs for the battalion. Each of the PADS teams must
extend survey control to two batteries. Even with the SCPs
conveniently located between the batteries, each PADS will
have to travel about 80 km to accomplish the mission. Since
this type of employment will be used against the initial attack,
ample time should be available to complete the survey before
the outbreak of hostilities.
(2) Forward area defense engagement coverage. In this
configuration, Patriot battalions are employed to protect a
frontline division against attacks. The batteries of the
battalion are positioned in the division rear area in a five-point
perimeter formation that looks much like a pentagon. When
the battalion is deployed in this formation, the topo survey
company or the div arty survey section must provide two
centrally located SCPs.
Figure 14-7. Area (belt) defense employment
14-10
C1, FM 6-2
c. Survey Requirements. The primary mission of the
PADS survey parties is to provide the radar and launchers
in each firing battery with timely survey control executed
to prescribed accuracies. The required data are determined
in the following order of priority:
Ž Orientation azimuth for the radar, north reference point
(NREF), and azimuth mark.
Ž Coordinates and height of the radar.
Ž Coordinates, height, and orientation azimuth for the
launchers.
(1) The primary missions of the SPCE are as follows:
Ž Collect, evaluate, and disseminate all available survey
data that might be used by the battalion.
Ž Maintain maps and files of survey data for the battalion
area of operation.
Ž Coordinate survey activities with higher, lower, and
adjacent HQ.
Ž Train battery personnel in hasty survey techniques.
(2) Since the Patriot system uses true north as a reference
and battery personnel will use grid azimuth to perform hasty
surveys, both grid and true azimuths should be provided to the
firing batteries. To ensure that survey data meet the required
accuracy, the PADS teams will establish all surveys by
performing 10-minute Z-VEL corrections.
(3) On receipt of the battalion OPORD, usually 4 to 6
hours before the battery movement, the RSOP officer, RSO,
or the chief surveyor will issue a warning order to the SPCE
and the PADS teams. Because of the distance to be traveled,
the PADS may be initialized before departing or initialization
may be performed near the new position if survey control is
available at the new position. The PADS teams should be
included in the recon party so that the necessary survey
operations can be started immediately after the new sites are
selected.
(4) The survey will be performed in accordance with the
battalion commander's guidance. In the absence of
commander's guidance, the recommended methods of
establishing the required survey control for the battalion,
according to priority, are as follows:
Ž PADS performing two-position plumb bob or
theodolite marks and using 10-minute Z-VEL
corrections.
Ž Field artillery surveyors (PADS and SPCEpersonnel)
using conventional survey methods.
Ž Patriot survey teams using hasty survey techniques
and the aiming circle (FM 6-50).
d. Survey Techniques. The techniques to be used in
surveying a Patriot battery (Figure 14-9) are discussed on
the next page.
Figure 14-9. Patriot battery area (five launchers)
14-11
C1, FM 6-2
(1) Establish the NREF and azimuth mark by the
two-position and azimuth mark method by using a plumb
bob. If the NREF line must be less than 100 meters, establish
the line by performing a position and azimuth mark with a
theodolite.
(5) Whether the Patriot battalion is organized under the
three-battery concept or the six-battery concept (Figure
14-12), the survey control required and the procedures for
performing the survey are the same for each battery.
Figure 14-10. Launcher site survey
(2) Establish the radar site by performing a position mark
with a plumb bob or theodolite.
(3) In surveying the launcher sites (LSs) (Figure 14-10),
establish the following for each launcher:
Ž An OS (located 10 to 12 meters behind the launcher
position).
Ž OL from the OS to the launcher position.
Ž Location of the launcher position.
To do this, set up the theodolite over the launcher position
and perform a position and azimuth mark by using the
theodolite. After entering data, be sure to apply 3,200 mils
to the azimuth displayed by the PADS (azimuth from launcher
to OS) to get the azimuth from OS to launcher. The
coordinates displayed will be to the launcher position and
the height to ground level of the PADS.
Figure 14-11. Establishing two SCPs (time critical)
(4) When time is critical, the PADS parties establish at
least two SCPs with azimuth marks within each battery
position. One will be near the radar site, and the other one
will be the center launcher position. The azimuth mark for
the SCP near the radar will serve as the NREF for the radar.
(See Figure 14-11.) Battery personnel will extend survey
control from these SCPs to the other four launchers by using
conventional and hasty survey techniques.
Figure 14-12. Patriot battery area (eight launchers)
14-12
C1, FM 6-2
Section III
DIVISION ARTILLERY SURVEY
The primary mission of div arty survey is to establish battalion SCPs and an OL for assigned or
attached firing and target-locating units. The div arty secondary mission is to recover and verify
existing control, provide survey tie-in points to adjacent division areas, and help battalion surveyors
whenever possible.
14-11. DIV ARTY SURVEY OFFICER
a. The div arty survey officer is the principal advisor to
the div arty commander and his staff on survey matters.
On the basis of the corps survey plan, he plans and
supervises the div arty survey and has staff responsibility
for all surveys performed by the div arty survey section.
b. The div arty survey officer must identify all units and
elements requiring survey control and ensure that these
requirements are met in his plan. Because of the number
and variety of installations in the division requiring survey
control, the div arty survey officer develops a survey plan
that is based on the priorities established by the div arty
commander.
c. Equal distribution of the survey workload increases
the speed of execution. When the div arty survey officer
tasks battalions and the TAB to perform surveys for various
installations, he must ensure that these missions are within
the capabilities of the battalion and/or TAB. The div
arty survey officer must coordinate with lower echelon
survey elements to avoid a duplication of effort.
d. The div arty survey officer must also maintain liaison
with the aerial fire support observer (A FSO). He must
determine the control requirements of the OH-58D aircraft
with respect to specific mission planning. Landing areas
collocated with the div arty TOC require surveyed
initialization points. The div arty SPCE provides data
from which the AFSO can get established control for
planning way points for his mission.
14-12. DIV ARTY SURVEY SECTION
a. The div arty survey section starts from SCPs selected by
the div arty survey officer. He selects these starting points
from either existing trig lists or from SCPs established by
engineer topo surveyors. If there is no existing control, the
div arty survey officer or chief surveyor will assume starting
data.
b. The div arty survey officer must use the survey section
effectively. The PADS teams are his primary survey assets,
but the survey team can be used to speed up survey operations.
Once the PADS teams have brought control to the forward
area by using 5-minute Z-VELs, the survey team using
conventional methods can extend control from PADS points
to nearby installations.
c. The preferred method for extending control from a PADS
point is a traverse closed on the starting point by using a
minimum number of traverse legs. The div arty SPCE helps
the survey team if needed. If survey control is not provided
and/or PADS cannot occupy existing control, the survey
team uses conventional methods to provide the PADS teams
with starting SCPs.
d. Div arty must operate on a 24-hour basis under the ALB
concept.
The mission of operating continuously and the
long distances in the div arty survey mission creates a need
for backup PADS teams. The survey section chief can
schedule the survey team as an alternate PADS team to
sustain the requirement of continuous operations. The div
arty chief surveyor supervises the survey execution and helps
coordinate between div arty, brigade SPCE, and other survey
echelons.
e. If one div arty PADS becomes inoperative, the div arty
survey officer distributes the workload between the remaining
PADS and TAB PADS teams. The personnel from the team
with the inoperative PADS combine with the survey team
and perform as a five-man conventional survey party.
14-13
C1, FM 6-2
Section IV
TARGET ACQUISITION BATTERY AND DETACHMENT
The TAB survey section provides survey supped for the Firefinder radar (AN/TPQ-37) and, when
tasked, for the IEW installations. The detachment PADS team is a corps asset that provides survey
support for corps-assigned AN/TPQ-37 radars.
14-13. TARGET ACQUISITION BATTERY
a. The TAB survey section consists of one PADS team and
a six-man survey party. Also located in the TAB is a survey
HQ element.
b. Survey requirements of the TAB are discussed below.
(1) Provide the Firefinder radar (AN/TPQ-37) with
azimuth, coordinates, height, vertical angle, and the distance
from the site near stake to the far stake.
(2) Provide IEW installations with survey control when
tasked by the div arty survey officer.
(3) Establish battalion SCPs when tasked by the div arty
survey officer.
c. Although the AN/TPQ-37 radars are the TAB surveyors'
standard mission, the div arty survey officer may direct the
TAB survey section to perform any mission throughout the
division area. To avoid duplication of the survey efforts,
the TAB must closely coordinate its survey plan with the
div arty survey officer.
d. When possible, the TAB survey will start from existing
SCPs, as do all survey echelons. When existing survey
control is not available, the TAB survey will start from an
SCP provided by the div arty survey section. If the TAB
has to assume starting control, they must close their survey
back on the starting point and convert their data to div arty
grid when available.
e. The TAB PADS team will use 5-minute Z-VEL
corrections to ensure the necessary accuracy to establish
battalion SCPs when directed. The PADS team can provide
control, using resection and astro observation, if they have
to go beyond the PADS limit of distance. The survey team
can use short closed traverses anchor resections to establish
starting control and update points for the PADS team. In
addition to providing conventional support, the survey team
will act as the relief PADS team during 24-hour continuous
operations. In the event the PADS becomes inoperative,
the HQ element will combine with the PADS team personnel
to form a conventional team. The TAB will then operate
with two conventional teams.
14-14. DETACHMENT
Detachments are corps assets in the form of a PADS team.
Their sole function is to bring control to corps-assigned
AN/TPQ-37s situated in the zone of operations.
Section V
SURVEY PLANNING AND COORDINATION ELEMENT
(CORPS AND BRIGADE)
The corps artillery SPCE is the planning and control element for survey operations. The FA
brigade SPCE may have a DS or general support reinforcing mission and is the controlling element
for all survey operations within its area of responsibility.
14-15. CORPS ARTILLERY SPCE
a. Maintain maps and overlays which show completed
The survey planning and coordination officer (SPCO) and
the corps chief surveyor (SFC) plan and coordinate survey
activities. Three survey computers (SGTs) are responsible
for the functions discussed below.
b. Keep a file of all SCPs and tie-in points established in
adjacent corps areas by div arty and TAB survey sections.
14-14
surveys, surveys in progress, and planned surveys.
C1, FM 6-2
c. Disseminate survey data via published trig lists and FM
secure radio over the corps artillery survey net. (See Figure
14-13 for the field artillery survey radio net.)
14-16. FA BRIGADE SPCE
a. The FA brigade SPCE, consisting of four members, is
the planning and coordination element that is the controlling
element for all survey operations within its area of
responsibility. The FA brigade may have a DS mission or
general support reinforcing (GSR) mission. When assigned
a DS mission, the FA brigade SPCE's mission is similar to
that of the div arty SPCE, and it coordinates its survey
requirement with the corps artillery. When assigned a GSR
mission, the FA brigade coordinates its survey requirements
with the div arty SPCE. Since the FA brigade does not
have an organic survey section and to minimize duplication
of the survey efforts, the SPCE must very closely coordinate
its survey requirements with the higher HQ (corps and div
arty SPCE).
b. The FA brigade SPCE mission requirements are discussed
below.
(1) Ensure common grid throughout the brigade area of
operation. This should be based on the grid provided by
corps artillery or div arty SPCE.
(2) Coordinate survey operations with higher, lower, and
adjacent units.
(3) Establish survey priority on the basis of the
commander's intent.
(4) Request, through the corps artillery SPCE, external
survey support and/or information from the corps engineer
topo survey element.
(5) When required, request external survey support and/or
information from the div arty SPCE.
(6) Disseminate survey information to its organic units.
(7) Gather, evaluate, and compile survey control
established by its organic units.
(8) Maintain maps and overlays of completed surveys,
surveys in progress, and planned surveys.
(9) Provide starting survey control data to its organic
units and tie-in point data between adjacent units.
(10) Advise and help battalions plan, conduct, and
evaluate survey training.
(11) Select sites for declination stations.
(12) Direct and coordinate tasked organizations of the
FA brigade survey elements to best accomplish overall survey
mission.
14-15
C1, FM 6-2
(13) Plan and provide survey control to other users (IEW,
advanced helicopter improvement program [AHIP], mortars,
and so on) when required.
(14) Direct and coordinate recovery of existing survey
control points.
Figure 14-13. FA survey radio net
14-16
C1, FM 6-2
14-17. COLLECTION OF
SURVEY INFORMATION
Information collected by the SPCE includes trig lists, reports
by the FA section at corps HQ, div arty and TAB survey
party reports, and FA battalion survey reports.
a. DMA Trig Lists. The SPCE obtains DMA trig lists as
part of the initial map issue to the div arty. The SPCE
retains one copy of each trig list as a reference record. Trig
lists are considered allied support material to the map supply
and are requisitioned through G2 channels. The areas of
current operations and prospective interest are the basis of
map supply to the div arty.
b. Reports by the FA Section at Corps Artillery
Headquarters Battery. In static situations, the FA section
at corps artillery HQ battery may periodically publish
consolidated lists of fourth-order SCPs established by the
survey parties from all division artilleries in the corps.
c. Div Arty and TAB Survey Party Reports. The div
arty and TAB survey parties report their progress daily to
the SPCE. Reports are accompanied by field notebooks
and complete computations on all surveys performed.
Members of the SPCE check and evaluate the data and enter
the required information on DA Form 5075-R (Artillery
Survey Control Point). (See Figures 14-14 and 14-15.) This
form is completed in duplicate for each fourth-order SCP.
One copy of the form is provided to the corps FA section,
and one copy is filed as a reference record. (A reproducible
copy of this form is included at the back of this book.)
d. FA Battalion Survey Party Reports. The survey parties
periodically submit survey information to the div arty SPCE
on DA Form 5075-R. Copies are retained as reference
records. Only survey control that the div arty, SOP, or
OPORD has directed the artillery battalions to establish are
reported. The div arty survey officer designates the points
to be established by battalions when the situation is such
that the establishment of these control points would contribute
materially to the expeditious delivery of FA fires. These
survey control points are of particular value in cases in which
FA battalions exchange position areas or when counterattack
plans are implemented and an abundance of survey control
is required in a general area to be occupied by the supporting
field artillery. They are designated with a specific purpose
in mind and then only when it is impractical to provide
fourth-order survey control points.
Figure 14-14. F r o n t o f D A F o r m 5 0 7 5 - R
14-17
C1, FM 6-2
14-18. MAINTENANCE OF
SURVEY INFORMATION
Present (solid-line symbols) and proposed (broken-line
symbols) artillery positions in the division area in brown.
The SPCE must maintain the information it has collected
in a usable form. A survey information map with overlays
and a survey information file are prepared to allow
information to be used.
The friendly situation and the enemy situation when it
might affect the planning or performance of survey in the
division area.
a. Information Map and Overlays. The SPCE maintains
an information map showing all SCPs in the division area
and adjacent division areas located to fourth-order accuracy
or higher. In addition, overlays to the map show the locations
of artillery units, possible position areas, surveys in progress,
proposed surveys, and other information required by unit
SOP. These maps and overlays should show the following
information:
Survey control points in black.
Completed surveys in brown.
TAB installations in blue.
Proposed surveys in green. When possible, surveys
proposed by div arty and TAB are included.
14-18
b. Information File. The SPCE maintains a survey
information file of trig lists and extracts of trig lists prepared
and issued by DMA and the Corps of Engineers. A record
is maintained of field notes and computations on control
points established by the div arty and TAB survey sections.
The SPCE submits periodic reports on surveys in progress
to adjacent div arty SPCEs and to artillery units operating
in the division area.
c. TACFIRE or AFATDS SCP Data Base. The SPCE
must ensure that known control points are entered into the
tactical fire direction system (TACFIRE) or advanced field
artillery tactical data system (AFATDS) SCP data base. SCPs
in the division area of interest and in the supported unit
areas of influence should be entered and updated. The SCP
data base must be kept current to decrease the possibility
of duplicate surveys and to rapidly exchange survey data
automatically.
C1, FM 6-2
This paragraph implements STANAG 2934.
d. DA Form 5075-R. DA Form 5075-R is used to permit
quick identification of survey control points. Figures 14-14
and 14-15 show the use of DA Form 5075-R. The front
of the form (Figure 14-14) provides blocks for the following:
Control point name and number.
Map sheet and series number.
Grid and geographic coordinates.
Altitude.
UTM zone and UTM square.
Marking method.
Accuracy of the data.
Notes.
Location diagram.
The reverse side of DA Form 5075-R (Figure 14-15) provides
blocks for the following:
Description of reference points.
(2) Computation comparison check. The computations
performed by the computers are compared to ensure that
both sets of computations agree.
(3) Closure check. A check is made to ensure that the
survey has been properly closed within fourth-order accuracy.
(4) Map verification. If the survey data pass the
procedure check, computation check, and closure check, the
data are plotted on the largest-scale map available to check
both the validity of the survey and the accuracy of the map.
If the map plots verify the recorder's field notebook
description, the survey is accepted. If the map plots do not
verify the recorder's field notebook description, the data are
subjected to a complete computation check. If necessary,
additional fieldwork is prescribed to determine whether the
map or the survey is in error. Any map errors detected by
survey personnel performing fieldwork should be noted in
the remarks column of the field notebook and reported to
higher HQ through G2 channels.
c. In addition to performing the functions just discussed,
SPCE personnel are equipped and trained to make the
following checks and computations:
Sketch of reference points.
Distance to reference points.
Grid bearing or azimuth to reference point.
Methods used in determining horizontal, vertical, and
azimuth control.
Verification information (unit, preparer, checker, date, and
notebook reference).
Traverse, triangulation, intersection, resection, and astro
computations.
Adjustment of all surveys to distribute minor errors in
distance and direction throughout all stations occupied in
the survey. Before adjustment, all surveys must meet the
minimum fourth-order closure requirements.
Swinging and sliding operation to convert survey data
from one grid to another.
14-19. EVALUATION OF
SURVEY INFORMATION
Transformation of coordinates and grid azimuths between
UTM zones.
a. The div arty SPCE must check the field records and
computations of the div arty and TAB survey sections. A
survey team operating in the field maintains a field notebook
containing a complete record of all fieldwork performed and
all DA forms on which computations are performed. On
completion of the survey, the field notebook, computation
forms, and results of the survey are forwarded to the SPCE
for checking, adjusting, and recording.
Conversion of geographic coordinates to grid coordinates
and grid coordinates to geographic coordinates.
b. The evaluation process is designed to verify the validity
of the surveys and consists of procedure checks, computation
comparison checks, closure checks, and map verification.
(1) Procedure check. All computations and values
recorded in the field notebook are checked to ensure that
proper procedures, specifications, and techniques were used
to complete the survey fieldwork to the required accuracy.
14-20. DISSEMINATION OF
SURVEY INFORMATION
Timely dissemination of survey information is equally as
important as maintaining a complete and accurate survey
information file. The SPCE maintains survey information
maps and overlays to aid in the rapid dissemination of survey
information to units and to aid the div arty survey officer
in preparing the division survey plan. In the div arty, survey
information is disseminated by personal visits by battalion
survey personnel, coordination and liaison visits by the div
arty survey officer, command and control systems, radio
and telephone, and field liaison between survey sections.
14-19
C1, FM 6-2
a. Battalion and TAB RSOs or their representatives should
visit the SPCE often to keep abreast of div arty survey plans
and to obtain survey control (trig lists) available in their
prospective areas of interest.
method of disseminating survey information because of
possible errors in transmitting and because of problems in
orally describing the survey station sketches shown on DA
Form 5075-R.
b. The div arty survey officer should visit the FA battalions
and the TAB often to coordinate and discuss survey operations
and requirements. During these visits, he should ensure that
the RSOs are aware of available control.
e. In the div arty, survey information usually is not
disseminated until it has been evaluated and adjusted. During
fast-moving situations in areas where limited survey control
is available, there may be exceptions. The div arty survey
section in the field may disseminate survey data directly to
the battalion sections as the data are determined. In this
case, the chief of the div arty survey section disseminating
the survey data will ensure that the battalion and TAB survey
officers are informed that the data provided are unchecked
and unadjusted. When the survey data are turned in to the
SPCE, the chief of the survey section will report which data
he has disseminated and to whom. The SPCE will then
ensure that the user gets the adjusted data when they become
available.
c. Survey data can be stored and rapidly trasmitted by using
command and control systems such as TACFIRE and
AFATDS. Unit SOP will dictate the procedures used to
access, store, update, and disseminate survey information
between echelons.
d. Survey information may be disseminated by radio or
telephone. However, security requirements outlined in the
unit signal operation instructions (SOI) must be observed.
Radio or telephone communication is the least desirable
Section VI
SURVEY IN SPECIAL ENVIRONMENTS
Survey operations must proceed regardless of environmental factors, such as climate and terrain.
Therefore, the type of environment must be considered. This section discusses some of the problems
that may affect surveyors in arctic, desert, jungle, and urban areas.
14-21. ARCTIC AREAS
a. Survey Operations. Normally, peacetime surveys are
planned to take advantage of the warmer months of the year
to avoid working under the varying terrain and climate
conditions found in the upper latitudes. In wartime, however,
survey operations are executed when and where needed and
cannot wait for ideal climate conditions. The summer season
has the advantage of better visibility, greater body comfort,
and fewer equipment malfunctions. The winter season
reduces transportation difficulties in river, lake, and tundra
regions. Survey control can be extended easily along
riverbanks; over the nearly level, treeless plains of the arctic
tundra; or across large bodies of water. When committing
survey elements to field operations in arctic regions or under
arctic conditions that are seasonal in the middle latitudes,
commanders must consider the effects of ice movement,
snowfall, prevailing wind, light refraction, and other
peculiarities. The proper use of authorized cold weather
equipment and field expedients will overcome most problems
caused by the cold. For detailed instructions on cold weather
operations, refer to FMs 31-70 and 31-71.
b. PADS Operation. The PADS operates without
performance degradation at temperature extremes between
14-20
-50°F (-45°C) and 125°F (50°C). It may be stored without
damage between -50°F and 160°F (71°C). Initialization,
which normally takes about 30 minutes, will take longer at
temperatures below -5°F (-20°C) or when wind blows into
the IMU heat exchanger. Using a vehicle enclosure, parking
behind a windbreak, or placing a blanket or an article of
clothing over the heat exchanger exhaust will improve
reaction time. Keep the batteries warm at temperatures below
-20°F (-29°C). Use the vehicle heater during operation.
Store batteries in a warm area when they are not being used.
WARNING
Contact with power supply fins may cause skin
bums at high ambient temperatures. Lead-acid
batteries that are not fully charged may freeze
and burst. Handle batteries as prescribed in TM
9-6140-200-14.
c. Other Field Operations. Survey accuracy depends
largely on factors that can be controlled in the field by the
survey officer, the chief surveyor, and the chief of the survey
section. These include instrument handling, equipment care,
C1, FM 6-2
and aids to maintaining body comfort. Surveying in the
arctic or under arctic conditions requires a lot of professional
judgement and common sense. All survey methods may
be employed subject to terrain and weather conditions in
the area of operation. Warmup time for electronic equipment
will be increased.
(1) Setting up instruments under bad weather conditions,
especially in snow, requires the use of field expedients. Brief
setups in snow can be accomplished by firming up a snow
base. Tamping will suffice for routine operations. Other
procedures are discussed below.
(a) Clear away the snow to reach the frozen but solid
earth.
(b) Drive stakes to form a trivet-like base for tripod
shoes.
(c) Use long tripod legs for setting up in deep snow.
(d) Use sharply pointed tripod shoes to facilitate setting
upon icy surfaces.
(e) Protect the instrument from wind, or accurate
readings will be difficult
(2) Proper daily care ensures against equipment failure
and delays in the field. Extreme changes in temperature
may induce internal stresses within an instrument.
Instruments should be kept outside overnight or in unheated
shelters for short periods of nonuse. When transporting
instruments in the field, make some arrangement for the
instrument to be carried outside the vehicle or in an unheated
cargo compartment. Tripods also should be left outside when
not in use. The BUCS (with batteries removed) can be
stored in temperatures down to -40°F, but it cannot operate
below 32°F (O°C). The proper lubricant for arctic use is
grease, artillery and automotive, military specification
MIL-G-10924, or an equivalent.
(3) Body comfort depends mainly on the protection
offered by issue clothing. The survey chief can improve
conditions by directing the digging of pits, erecting
windshields, or building up snowbanks to reduce the intensity
of exposure over extended periods. Utility stoves should
be used for heating nourishing liquids and keeping the fingers
warm. An instrument can be modified by providing enlarged
nonmetallic operating knobs or by wrapping standard knobs
with adhesive tape. This facilitates manipulation of the
instrument and helps keep the fingers from being injured.
Head and hand coverings become a problem for the
instrument operator and the recorder. Layer gloves and layer
head coverings provide a practical combination of warmth
and maneuverability. An easily removed hood over an
ear-covering headpiece is practical for most conditions.
Safety precautions are discussed below.
(a) Do not touch metal with any part of the bare skin.
(b) Make use of equipment furnished for protection of
the eyes against wind and glare.
(c) Always use the buddy system in surveying. Do not
go out alone.
(d) Always carry a first aid kit.
(e) Practice personal hygiene as coveredin FM31-70.
d. Survey Control. In most arctic areas, especially on the
tundra or in heavily forested regions and away from centers
of civilization, preestablished control will be minimal.
Survey control that does exist will be difficult to locate in
areas of heavy snowfall and high winds. Topo support is
essential to establish the common grid. Map spottings, when
maps are available, are almost impossible because of the
lack of definable natural and man-made objects. The most
probable solution for the extension of survey control (if topo
support cannot be provided) is for the div arty survey officer
to assume position control; use the PADS, astro observation,
or the SIAGL (latitude of operation permitting) for direction;
and start the common grid there. Each installation or unit
will then convert to common control as it enters the divisional
survey net.
14-22. DESERT AREAS
Field artillery survey in a desert environment lends itself to
some major problems in equipment, methods, and operations.
Problems not experienced in other environments are prevalent
during desert operations. Initially, desert operations seem
to be perfect for survey w ith long lines of sight, clear traverse
lines, and cloudless skies for celestial observations.
However, the desert is no utopia for the surveyor. Some
of the problems encountered are described below.
a. Equipment. Optical instruments operated in extreme
heat can have some major interior and exterior physical
problems. Experience has shown that at 100°F, the survey
instrument leveling vials increase about 2 graduations past
the true center. Therefore, at 120°F, the instrument operator
may not be able to level the instrument because of bubble
expansion. To counter this, instruments should always be
shaded. The direct rays of the sun can and will cause optical
distortion and internal stress. Before moving to a desert
environment, operators and supervisors must ensure that
proper maintenance is performed and lubricants are applied
to and maintained in the instruments. The scoring effects
of sand and grit on the instrument optics require that the
instrument lens covers be in place when the instruments are
not being used. The major problems in desert operations
are caused by heat waves. Distances between stations are
severely limited because of heat wave distortions. Consistent
readings at occupied stations are nearly impossible to achieve.
14-21
C1, FM 6-2
Operator eye fatigue is common and necessitates frequent
operator changes. Beause of heat wave distortion,
conventional survey operations and PADS operations
requiring optical transfer should be avoided. The BUCS
can be stored in temperatures up to 140°F (with batteries
removed), but it cannot operate above 113°F (45°C). If
absolutely necessary, conventional survey operations will
have to be conducted during the hours of darkness or during
early morning and late afternoon.
b. Survey Control. Survey control in the desert is very
fleeting in nature. The lack of definable natural and
man-made objects increases the problem of permanent
control. Topo surveyors must make every effort to provide
starting control for the division survey section. Established
survey control dates from the desert colonial periods and,
although scarce, it is accurate. However, control that can
be identified and located one day may be obscured by sand
the next. If these control points are constructed of anything
valuable (for example, metallic substances of any kind), local
civilians will dig up and carry off the station markers. In
establishing control, efforts must be made to camouflage or
immobilize control points. Use of the existing road networks
and road junctions is another way of ensuring that control
is available when it is required. Burned-out armored vehicles
and destroyed fortifications also can be used as control points.
When operating in the desert, the survey officer should ensure
that all control possible within the zone of operations is
recovered and verified. It should be understood that control
in the desert is, at best, only temporary in nature.
c. Techniques of Conventional Desert Survey.
Conventional surveys conducted in a desert environment
require special considerations. In any other area, the primary
means of extending control is traverse. However, in the
desert, the distance involved and the lack of control indicate
the primary means of extending control will be triangulation.
If traverse has to be used, night traverses will be common.
If night surveys are required, parties will have to be
augmented with additional personnel. Light discipline will
be of great importance because lights can be seen in the
desert to distances of about 8 miles. Trig traverse is an
excellent means of extending control in desert operations.
The use of astro observation, simultaneous observations, and
the SIAGL to start and extend directional control will be
of critical importance to the surveyors.
d. Personnel. Personnel acclimatization is an important
factor in desert operations. It can be assumed that if our
current deployment policy does not change, there will be
no time for acclimatization. Surveyors will be deployed
from the continental United States (CONUS) right into a
desert environment. Care should be taken to ensure that
all personnel who might possibly be employed in this type
of environment are trained in survival techniques.
14-22
14-23. JUNGLE AREAS
a. Survey Operations. Survey operations in the jungle pose
many problems not encountered in other environments.
Some of these are the foreboding appearance of the jungle,
the oppressive humidity and heat, the unfamiliar noises, and
the loneliness one feels in the jungle. In addition to the
physical and psychological effects of working in the jungle,
the FA surveyor will be aware immediately of the lack of
adequate maps. The maps that are available often are
inaccurate except for locations of coastlines and principal
rivers. For a more detailed discussion of jungle operations,
refer to FM 90-5.
b. Survey Control. Because of the inaccessibility of jungle
areas and since adequate maps do not exist for most areas,
the establishment of survey control and the common grid
is a primary consideration of the commander.
(1) The extension of survey control should not depend
on preestablished control, which in most jungle areas is
minimal and at best difficult to recover and identify. One
solution is for the div arty or battalion survey officer, using
available maps or map products, to assume control; to use
the PADS, astro observation, the SIAGL, or simultaneous
observation for direction; and to initiate the common grid.
Each unit will convert to common control when it ties into
the division survey control net. Map spottings with available
maps or photomaps may have to suffice for position control
at firing unit locations.
(2) Normally, FA firing positions are in natural clearings.
This usually will permit a position area survey to tie in the
firing batteries relative to each other. Direction can be
obtained as described in (1) above. One possible solution
for the extension of the common grid is the use of gridded
mosaics or other photomap products.
c. Conventional Methods. Survey control maybe extended
through the jungle by pursuing traverse procedures. It will
be difficult and time consuming and normally will require
that a security force go with the surveyors. Using
triangulation and resection techniques is most difficult, since
line of sight is extremely short or nonexistent. Target area
survey and connection survey usually are very restricted or
impossible. In any case, survey in the jungle requires the
imagination and initiative of all survey personnel.
14-24. URBAN AREAS
a. In most military operations, the type of terrain is a prime
factor in planning, coordinating, and executing a unit mission.
This is especially true for survey operations conducted in
C1, FM 6-2
and around villages, towns, cities, and other built-up areas.
The presence of buildings and man-made changes to the
landscape greatly affect conventional survey operations and
also must be considered during PADS operations.
b. The tactical situation is a strong influence on survey
operations in built-up areas. The enemy can be well hidden
by using roofs and upper stories of buildings, sewer systems,
subways, and other underground structures. Enemy obstacles
(barricades, booby traps, and minefield) may deny the use
of certain terrain needed as routes for extension of survey
control. Communication between survey assets may be
hampered by the limited range of FM radios within built-up
areas.
c. Line of sight limitations in urban areas and the possibility
of widespread weapon positions will increase the number
of survey stations. Required OPs must be located on rooftops,
towers, or other high structures. Also, more OPs may be
needed to observe all areas of concern and to ensure accurate
target locations.
d. Targets of opportunity generally will be exposed to
observes for brief periods. Also, political and tactical
considerations will demand pinpoint accuracy in locating
and destroying targets. Destroying key facilities and creating
severe obstacles to friendly troops must be weighed. For
a detailed discussion of urban operations, see FM 90-10.
14-23
FM 6-2
CHAPTER 15
SURVEY PLANNING
The purpose of artillery survey is to provide firing and target-locating assets
with a common grid. Common survey control allows the commander to
tactically employ his units with a guarantee of accurate and timely fire
support. This allows him to mass fires of subordinate units, to store and
transfer target locations for future attacks, and to limit vulnerability of firing
units. Planning for artillery surveys is based primarily on the planned
positioning of firing units and TA assets and the commander’s accuracy
requirements.
15-1. CONDUCT OF PLANNING
a. Surveys are planned to ensure that all required
control is provided in the correct place and
at the time required. The plan distributes work
evenly among teams and eliminates duplicate work.
Planning is based on meeting as many survey
requirements as possible under the given conditions
and always providing the best available survey
control to using units.
Direction is the most
important element of survey control.
Therefore,
when time is critical, the plan must reflect the
requirement to rapidly extend direction throughout
the area of operation and later extend coordinates
and height.
b. Survey planning is conducted at all echelons
at the same time.
Provisions should be made
to link together all surveys conducted in the
area. Normally, the surveyors of div arty HHB
provide survey control points to all assigned
and attached battalions or separate batteries. Thus,
they tie together the surveys of the division
firing and locating elements.
The TAB and
battalion surveyors survey their organic and attached
elements and help other units as directed. The
degree of accuracy, speed of execution, and priority
of work are given in the commander’s guidance
or are set by the S3 from the commander’s
guidance.
c. Artillery units at all levels start survey operations
They do not
before occupation of position.
wait for higher-echelon survey control to be established
in the area.
Firing and target-locating units
must work from the best available data and
improve the data as higher-order survey becomes
available.
d. Fourth-order survey sections are organic to
the div arty HHB and TAB to provide survey
control for assigned and attached units of the
division.
Each artillery battalion has an organic
These sections are
fifth-order survey section.
organized into survey teams and equipped according
to the modification tables of organization and
equipment (MTOE) for the unit.
The concept
of employment of these sections is based on
the guidelines below.
(1) Div arty. Provide all organic, attached, and
reinforcing artillery battalions, TA assets, and separate
batteries with common direction, coordinates, and height.
(2) TAB. Provide common direction, coordinates, and
height for the TA assets of the battery. Provide SCPs for
other units as directed by the TAB commander.
(3) Battalion. Provide common direction coordinates,
and height for all firing batteries and targeting devices that
are assigned or attached to or reinforcing the battalion and
mortars.
15-1
FM 6-2
e. For the purpose of planning a survey, installations may
be separated into groups according to the accuracy of survey
required. Requirements and position considerations are
shown in Table 15-1.
(1) Fourth order. Fourth-order survey control is required
at firing battalion and separate battery SCPs.
Table 15-1. Survey installations
15-2
FM 6-2
(2) Fire order. Fifth-order survey control is required
by firing and target-locating installations. Some installations
require 0.4-mil or 0.5-mil accuracy for direction. Care must
be used in selecting a method to establish direction for these
installations. The requirements for CEWI sites should be
addressed by local SOP or coordinated by the div arty survey
officer.
requirements. This checklist is not inclusive and should be
modifed to meet situations) requirements.
b. Corps Artillery SPCO. The responsibilities of the SPCO
associated with the corps survey effort are discussed below.
Figure 15-1. FSCOORD checklist
(3) Hasty survey. All firing and target-locating elements
requiring survey must be able to use hasty survey techniques
to provide the best available survey control rapidly. The
hasty survey techniques preferred for a particular system
are covered in the applicable field manual. For example,
FM 6-50 prescribes hasty survey techniques for FA cannon
batteries.
15-2. SURVEY PLANNERS
Survey planning is performed by many individuals at many
levels. Some of these planners are discussed below.
a. Artillery commander or FSCOORD. The maneuver
commander initiates the requirement for survey planning
when he issues guidance to the FSCOORD. He does so
by stating his scheme of maneuver, rate of movement,
anticipated enemy threat, and critics) phases of the battle.
The FSCOORD analyzes the commander’s guidance to
determine the need for passing of target information,
first-round fire-for-effect accuracy, and massing of fires. He
weighs his analysis against the ability to adjust fires, fire
registration missions, and rapidly engage targets from new
position areas. The concept for a survey plan to provide
common survey control is thus begun.
(1) The FSCOORD then must extract from the maneuver
commander’s guidance information that will allow him to
visualize the survey requirements for fire support (FS) assets.
The FSCOORD can gain most of the information by
reviewing the scheme of maneuver, rate of movement, effects
required on high-payoff targets, and accuracy requirements
for TA sensors. He must also determine whether it is more
important to have survey at the guns or TA assets first.
(2) Each artillery commander is responsible for
establishing common control throughout his area of
operations.
The FSCOORD must disseminate to the
appropriate artillery battalion HQ the established accuracy
requirements in survey terms. Additional requirements or
guidance derived by the FSCOORD must also be
communicated.
This should either be done through
face-to-face coordination or through the S3. The survey
officer must be included in this coordination. He should
advise the FSCOORD and/or S3 on his current survey
capabilities and limitations. Figure 15-1 is a checklist for
use by the FSCOORD as an aid in determining survey
15-3
FM 6-2
(1) Know the survey requirements of all crops units
(Figure 15-2) and the survey capability of those units.
(2) Coordinate with the corps G2 to get intelligence
estimates of the proposed work areas to include the following:
Ž Enemy activity.
Ž Friendly forces.
Ž Other optional connstraints.
(3) Coordinate with the crops G3 plans to get the
following:
Ž Current and planned positions of corps artillery units.
Ž Unit movement plans.
Ž Dates and times of movement.
Ž Priority of unit movement.
This information used in planning and coordinating includes
IEW systems requiring survey in support of corps missions.
(Refer to Figures 15-3 and 15-4 for corps survey plan—in
progress and future surveys overlay.)
(4) Make contact with the survey company of the
engineer topo battalion and obtain necessary details from
the commander (for example, attached platoon, location of
company SPCE, and names of points of contact). The
engineer topo battalions’ survey company supports the field
artillery and sir defense artillery with third-order horizontal
and vertical control points and azimuth marks for EAC down
to division and separate artillery brigades on a 24-hour basis.
Topo survey augments FA survey requirements with the
following:
Ž EAC—two SCPs per Patriot battalion.
Ž Corps area-eight SCPs each 24-hour period and one
SCP per div arty or separate brigade each 24-hour
period.
Ž PADS—starting and closing SCPs are provided at a
maximum interval of 25 km.
Ž MLRS—stsrdng and closing SCPs are provided at a
maximum interval of 30 km.
Figure 15-2. Units requiring survey within a corps
15-4
FM 6-2
Figure 15-3. Corps survey plan—in progress
15-5
FM 6-2
Figure 15-4. Corps survey plan—future surveys overlay
15-6
FM 6-2
(5) Make necessary arrangements with headquarters and
headquarters company (HHC), corps for administrative and
logistical support of the topo survey platoon.
(6) Arrange and coordinate with the corps aviation
company for aviation support if requested by the survey
platoon leader of the engineer topo survey company.
(7) Maintain a close working relationship with the topo
survey platoon leader or survey technician, the survey officers
of corps artillery units, and the div arty survey officers.
This coordination will ensure timely three-way flow of
information concerning survey operations and data collection.
It will also enhance timely completion of the survey mission.
c. Div Arty Survey Officer. The div arty survey officer
is the survey platoon leader of div arty HHB. As such, he
initiates tactical survey planning. He is responsible to the
div arty commander for the execution of the survey plan to
establish common survey control (the common grid)
throughout the division area. He coordinates all artillery
survey operations in the division to ensure effectiveness and
to reduce duplication of effort. This includes the activities
of the div arty SPCE, which is vital to the coordination of
the survey effort. The div arty survey officer requests
external survey support as required.
He plans the
employment of all organic fourth-order sections in the
division. His plan is in accordance with the commander’s
guidance as interpreted by the S3. The locations of division
tie-in points must be coordinated with adjacent div arty survey
officers for establishment of a corps common grid. As the
coordinator of div arty survey resources, the survey officer
must advise the commander and staff on all matters pertaining
to the following:
Ž Survey requirements.
Ž Techniques.
Ž Capabilities.
Ž Problem areas.
d. Div Arty Chief Surveyor. The div arty chief surveyor
is the technical expert on surveying in the div arty. His
primary duty is to advise the div arty survey officer. He
must have wide experience in the employment of FA
surveyors in support of all systems requiring survey data.
He must—
Ž Be prepared to assume the duties of the survey officer.
Ž Brief the staff on survey and recon matters.
Ž Formulate, implement, and supervise the execution of
the survey plan.
Ž Train surveyors in proper survey procedures.
He works closely with the TAB and battalion chief surveyors
to ensure complete undemanding of the div arty survey
concept. He also supervises the div arty SPCE to ensure
effective collection, evaluation, and dissemination of survey
data.
e. TAB Survey Officer. The TAB survey officer is
primarily concerned with extending survey control to organic
TA assets requiring survey control. He receives a survey
order from div arty survey officer and plans the employment
of his section to accomplish the mission. The TAB survey
officer must be ready to assume the duties of the div arty
survey officer when directed. In coordinating the div arty
survey effort, the TAB survey section may be assigned
responsibility for other installations (for example, battalion
SCPs) and may also assume SPCE functions.
f. TAB Chief Surveyor. In planning the TAB survey, the
chief surveyor must work closely with other section leaders
of the TAB in determining the locations of the required
positions. Since the TAB will be required to help establish
the common grid, the TAB chief surveyor must have a
thorough knowledge of the div arty plan and be prepared
to help in its implementation.
g. Battalion RSO. The battalion RSO is responsible for
placing organic and attached firing TA elements on a common
grid. His first priority is to establish common directional
control. Other priorities are listed in the commander’s
guidance or are derived by the S3. The RSO coordinates
the placement of the battalion SCPs with the div arty survey
officer. He also coordinates with the RSO of any R artillery
unit to ensure that units are on a common grid. The use
of a common grid allows accurate transfer of target data
between units. When required, the RSO and his HQ element
(chief surveyor and driver) combine with the survey section
to speed up operations such as setting up reflectors and
computing data. The battalion RSO performs reconnaissance
for the battalion to include selection of routes and evaluation
of positions within the position area. He works with the
S2 and S3 to determine areas requiring reconnaissance and
helps the battalion commander in his reconnaissance. The
RSO, as the technical advisor for survey in the battalion
must monitor an effective hasty survey training program.
The ability of the firing units to provide themselves with
some form of survey greatly improves their effectiveness
and allows the commander to mass fires of his subordinate
units sooner.
h. Battalion Chief Surveyor. Responsibilities of the
battalion chief surveyor parallel those of the div arty and
TAB chief surveyors. He must advise and perform technical
planning and coordinate the work of the survey team. He
must be prepared to perform the duties of the battalion RSO
and advise the battalion staff on survey and recon matters.
15-7
FM 6-2
15-3. ESSENTIALS OF A GOOD
SURVEY PLAN
More extensive survey planning is required in areas where
survey control is limited.
In formulating the survey plan, the survey planner must
remember and strive to meet certain essentials. The survey
plan must meet the essentials discussed below.
(2) Priority. The priority of work assigned is either listed
in the mission or commander’s guidance or derived from
the mission by the S3. The priority of work affects the
order in which the plan is executed or the type of survey
performed.
a. Provide Required Control. The plan must provide
survey control within the required accuracy to all installations
that require survey.
b. Provide for Checks. Whenever possible, the plan must
provide for cheeks; for example, closed surveys and alternate
bases. Each member of the survey team continuously makes
checks as a matter of standard practice.
c. Be Simple. The plan must be understood by all survey
personnel. Work that is unnecessary or that exceeds the
required accuracy must be avoided.
d. Be Timely. The plan must be capable of execution in
the time allotted.
e. Be Flexible. The plan must be capable of being changed
if the situation warrants.
f. Be Adaptable. The plan must be adaptable to the
following:
Ž Terrain.
Ž Situation.
Ž Personnel available.
Ž Weather.
Ž Equipment.
15-4. FACTORS AFFECTING SURVEY
PLANNING
In formulating the plans by which the survey mission is to
be accomplished, the survey planner must consider the factors
of mission, enemy, terrain and weather, troops and time
available (METT-T). The factors of METT-T cannot be
considered independently because each is related to the other.
a. Mission. The tactical mission of the unit determines the
time available, the area to be surveyed, the accuracy, and
priority of the survey effort. It is the basis of the survey
mission and determines the influence other factors have on
the survey.
(1) Starting control. The location of existing survey
control or the establishment of control by a higher echelon
of survey affects the time required to extend control. Survey
operations are concurrent at all echelons. When starting
control is not available, the starting data must be assumed.
The necessary survey operations are started immediately.
15-8
(3) Number of installations. The number and locations
of installations to be surveyed must be considered primarily
with respect to time and troops available. The survey
operations required to locate a few widely scattered
installations often take more time and/or personnel than
would be required for many closely grouped installations.
In the survey plan, the survey tasks should be allocated so
that the various survey teams complete their portion most
expeditiously.
b. Enemy. The enemy situation has a strong influence on
survey operations, since the disposition of troops may
interfere with or restrict the movement of survey personnel
and their equipment. Restrictions on communications, such
as radio silence and enemy jamming, can greatly reduce the
effectiveness of survey teams. The ability of the enemy to
interfere with survey operations by denying use of terrain
or routes is of prime importance. When survey operations
are restricted, the commander should give priority of survey
to those units supporting the main attack. FA surveyors
must be able to implement suppressive fire immediately if
they receive enemy fire. Terrain and cover must be used
as much as possible. Unit SOP should provide for actions
to be taken by survey teams that came under fire.
c. Terrain and Weather. The terrain and weather through
which survey control must be extended are a primary factor
in determining the methods of survey to be used. The survey
planner must be so familiar with the effects of terrain and
weather on survey operations that he can promptly and
properly advise his commander on the time and personnel
requirements. Adverse weather greatly reduces the capability
of survey teams. Fog, rain, snow, heat or dust can reduce
visibility to the extent that observation through an optical
instrument is impossible. When visibility is poor, the
commander may choose to put his survey effort on accurately
locating his radar so that it can locate his firing units. In
this case, the SIAGL would be used to establish common
direction. Extreme heat or cold can also reduce survey team
efficiency and increase the time needed to complete the
survey.
d. Troops. The survey personnel and equipment available
to perform the survey mission greatly affect the plan. The
status of training determines the methods available and time
required to perform survey, The availability and operability
of survey equipment dictate the methods used in the plan.
FM 6-2
e. Time. The time available to complete the survey
operation is the most critical factor in planning. Survey
planners must use the survey techniques necessary to provide
the best survey data within the prescribed time. A trade-off
between accuracy and time may have to be made, depending
on the tactical situation. The commander makes the decision
to allow decreased accuracy before the survey starts or to
accept decreased accuracy on completion of the survey.
15-5. METHODS OF SURVEY
In addition to being able to evaluate the factors that will
affect the survey, the survey planner must know the methods
of survey that might be used and the advantages and
disadvantages of each. The method chosen to provide survey
control depends on the factors of METT-T. PADS survey
supplemented by conventional methods is the primary means
of executing the survey order.
a. PADS Surveys. The main advantage of the PADS over
conventional methods is its speed. Disadvantages of the
PADS include the following:
Ž Reliance on the availability of survey control.
Ž Mode and route of travel.
Ž Restrictions on mission time and radial distance from
the update point.
These are the main considerations in planning PADS
operations. The time and distance factors used for planning
PADS missions are shown in Table 15-2.
Table 15-2. Time and distance factors—PADS mission
b. Conventional Survey Methods. Conventional methods
of survey may be used-exclusively to extend or establish
survey control if the PADS is not available. When the PADS
is available, conventional methods are used to supplement
PADS operations. Conventional teams provide update points
for the PADS teams as required. This reduces the need to
backtrack to close the PADS survey. Required installations
along the route taken by conventional teams in establishing
update points are surveyed to save time. Simultaneous
observation is used to quickly establish direction before
PADS teams arrive at installations. The conventional survey
team gives the survey plainer flexibility. This allows the
plan to be tailored to fit the factors of METT-T and allows
sustained PADS operation by rotation of survey personnel.
Conventional survey methods are as follows:
Ž Traverse.
Ž Triangulation.
Ž Intersection.
Ž Resection.
(1) Traverse. Traverse is the most suitable conventional
method for most survey operations. It is a rapid and flexible
means of extending control. Traverse does not require es
much reconnaissance as triangulation and is extremely easy
to control in the field. Traverse is ideally suited for survey
in gently rolling or flat terrain or for extending control along
roads and trails. For planning purposes, a well-trained
traverse team can extend control over open and gently rolling
or flat terrain at a rate of about 2 km per hour with the
SEDME-MR or 1 km per hour with a 30-meter steel tape.
15-9
FM 6-2
The use of offset legs to locate radar positions and other
points can reduce the time required for the traverse. Offset
traverse legs are not used to carry control, and an error
made during the offset leg fieldwork will not affect traverse
closure. Therefore, the fieldwork must be carefully checked.
(2) Triangulation. Triangulation is a means of extending
control over long distances. It is ideally suited for survey
in difficult terrain and for crossing obstacles. The primary
disadvantage of triangulation is the amount of time required
for reconnaissance. For planning purposes, triangulation
requires about 30 minutes per station plus time for
reconnaissance and travel between stations. Triangulation
schemes are not as flexible as traverse schemes, since all
stations in a triangle must be intervisible. Reconnaissance
for triangulation generally requires as much time as the
fieldwork, especially in extensive triangulation schemes. If
the distance-measuring equipment is operational, traverse is
preferred because it requires less time and fewer personnel.
(3) Intersection. Intersection is a method of triangulation
in which only two angles in a triangle are measured. It is
used to locate critical points, to establish update points for
the PADS, and to survey firing and target-locating elements.
When control is extended from a point established by
intersection, the survey must be closed on another known
point. The only exception to this is when intersection is
used to locate 01 and 02 of the target area base.
(4) Resection. Resection is a method of obtaining control
from distant points of known control that can be seen but
not occupied. Resection is used to—
Ž Locate firing and target-locating elements.
Ž Establish update points for the PADS.
Ž Locate 01 and 02 of the target area base.
Ž Close a survey.
Ž Check a location established by some other method
of survey.
If a point located by resection is used to extend control, the
survey must be closed on another known point. The only
exception to this is when resection is used to locate 01 and
02 of the target area base.
15-6. STEPS IN SURVEY PLANNING
The steps in planning a survey are generally the same as
the normal small-unit troop-leading steps. They are the
procedures by which a commander issues instructions to his
subordinates so that he can accomplish his mission. The
lower the echelon, the more simple, direct, and rapid the
process. Once the battle starts, orders and responses must
be fast, effective, and simple. This requires teamwork.
15-10
Troop-leading steps should be an instructive and automatic
way of thinking for section leaders and commanders.
Without detailed instructions, commanders must turn a
mission order into actions to support the plan of the next
higher commander. Elaborate troop-leading procedures are
useless if they slow the response of the force. The eight
troop-leading steps are as follows:
Ž Receive the mission.
Ž Issue a warning order.
Ž Make a tentative plan that will accomplish the
mission.
Ž Start the necessary movement.
Ž Reconnoiter.
Ž Complete the plan.
Ž Issue the order.
Ž Supervise.
Troop-leading steps are not rigid. They can be changed to fit
the mission and the situation. Often, some steps are taken at
the same time while others are considered continuously
throughout the operation. When there is a lack of time, certain
steps may be left out. The troop-leading steps as they apply
to survey operations are discussed below.
a. Receive the Mission. Leaders receive a mission in either
an oral or written OPORD or fragmentary order (FRAGO).
Upon receiving the order, the leader analyzes the mission
and plans the use of available time. The FSCOORD or S3
gives the survey officer a mission. It may consist of general
areas to be surveyed or specific locations for battalion SCPs,
platoon area SCPs, molar positions, and such.
b. Issue a Warning Order. The leader issues a warning
order that gives his subordinates the mission and the time
it starts. He issues it early enough for the section to plan
and prepare. Normally, warning orders are issued through
the chain of command. In that way, all personnel are kept
informed of what they must do and why they must do it.
The warning order should include the location of a nearby
SCP or prominent landmark. Preoperation checks of vehicles
and equipment are completed.
c. Make a Tentative Plan. The survey always connects
required control with known control. The first step in
formulating a survey plan is to gather information on the
area, enemy situation, and any usable known control. A
map reconnaissance is made to tentatively determine the
methods of survey.
FM 6-2
(1) Gather information. From the commander’s briefing,
the survey officer gathers vital information that influences
the planning of his survey. This information should pertain
to—
Ž The situation to include the following:
- Mission of the units.
- Status of registration.
- Time available.
- Zones of fire.
- Friendly positions.
Ž Routes, communications, minefield, contaminated
areas, and restrictions on modes of travel.
Ž Support to R units, to allies, or to priority units.
(2) Make map reconnaissance. After attending the
commander’s briefing and issuing a warning order to alert
his personnel, the survey officer, using any suitable map or
map substitute, makes a thorough map reconnaissance. In
doing this, he follows a specific procedure to ensure that
full consideration is given to all factors. This procedure,
in order, is discussed below.
(a) Map-spot installations. Known control and those
installations requiring survey control are plotted on the map.
Restricted areas and other information relative to the area
of operations are also plotted.
(b) Select a tentative plan. All the factors that affect
survey (METT-T) are fully considered, methods are chosen,
and a tentative plan is made. Particular attention is placed
on the accessibility of installations.
(c) Consider time. An estimate of the time required
to execute the tentative plan is made. If the survey mission
cannot be performed within the allotted time, the plan is
modified or an appropriate recommendation is made to the
commander. The planner may recommend the following
Ž Extra personnel be made available.
Ž Div arty support be requested.
Ž More time be allowed for survey.
Ž Location of certain installations be delayed.
Ž Accuracy for certain installations be relaxed.
(d) Determine critical areas. Areas that require
detailed ground reconnaissance are identified.
d. Start Necessary Movement. The survey planner must
now make good use of the time available so that the section
will be in the area to be surveyed at the required time. If
the section must move a long distance, it should start the
move immediately on the basis of first rough plans.
e. Reconnoiter. After the map reconnaissance, the survey
planner must make a ground reconnaissance as detailed as
time permits. The tentative plan selected during the map
study is changed as required by the terrain. Particular
emphasis should be placed on critical areas. If necessary,
indications are made to other survey planners or team chiefs
at points where tentative plans may need revision or close
coordination. A scale sketch of the survey is an easy way
to summarize information determined from the ground
reconnaissance. Since a PADS team can provide survey
data as it reconnoiters, greater emphasis must be placed on
efficiency of movement through the area.
f. Complete the Plan. Reconnaissance may not change the
plan, but it certainly adds detail. The plan must be modified
to fit all the information gained from the ground
reconnaissance.
g. Issue the Order. A verbal survey order is issued, if
possible, from a vantage point overlooking the area to be
surveyed.
The survey order follows the standard
five-paragraph OPORD format. Continuing operations may
require the use of a FRAGO.
h. Supervise. A leader must continually supervise the
preparation for and execution of the mission. Constant
supervision is as important as issuing the order. Along with
supervising, the survey HQ element must help the
conventional team as required. This help will supplement
PADS operations and speed up the survey mission.
15-7. THE SURVEY ORDER
The survey order contains detailed instructions
to each survey team not covered by local SOP.
It gives general information needed for the efficient
accomplishment of the survey mission. The survey
It generally
order is written or issued orally.
follows the same sequence as the OPORD. Often,
because of the tactical situation and wide dispersal
of units, parts of this order may be issued
by radio or wire or both.
a. The format for a five-paragraph survey order is shown
in the example on page 15-12.
b. FRAGOs include the information in paragraphs 2 and 3
of the survey order and anything else that has changed since
the last order.
15-11
FM 6-2
15-8. PRINCIPLES OF A SURVEY SOP
a. An SOP standardizes procedures for those phases of
operation the commander wants to make routine. These
procedures are to be followed in the absence of specific
instructions. The SOP of a battalion or higher-level HQ
should contain a section on survey. The SOP for each level
must conform to the SOP of the next higher level. Therefore,
the survey portion of the SOP at each FA level should include
only those survey procedures the commander wants to make
standard throughout his command. Survey items the
commander wishes to make standard only for the survey
section of his HQ should be in the SOP for that particular
section. A survey SOP does the following:
Ž Simplifies the transmission of the survey plan.
Ž Helps perfect the training of survey personnel.
Ž Promotes teamwork through understanding.
Ž Expedites survey operations.
(1) Simplify the transmission of survey plans.
Instructions included in an SOP need not be restated in the
survey plan. Many details on operations, measurements, or
methods of survey may be outlined in the SOP. This
eliminates the need for a lengthy and bulky survey plan or
order. However, inclusion of instruction in the SOP does
not prevent the survey officer from restating these instructions
in the survey plan for emphasis.
(2) Simplify and perfect the training of survey personnel.
Establishment of standard procedures for survey operations
ensures uniform training and minimizes the need for special
instructions.
Through the continued use of standard
procedures, survey personnel become more proficient in their
operations.
(3) Promote teamwork and understanding. Standing
operating procedures ensure uniform performance of survey
operations and minimize the time and effort required for
coordination. This is particularly true in those units that
use more than one survey team.
(4) Expedite survey operations. When personnel become
familiar with and use standard signals, techniques, and
procedures, they will do their tasks in minimum time.
Furthermore, the use of standard procedures reduces
confusion and eliminates unnecessary survey operations.
15-12
FM 6-2
b. To be effective, a survey SOP must be brief and must
conform to established doctrine. If the SOP is too long and
detailed, it loses its value as an instrument of ready reference.
It must be flexible, since it cannot cover every possible
survey situation or method. The SOP should give survey
personnel enough latitude to adapt survey requirements to
different situations rather than specify various types of
problems that may or may not exist in the field. The SOP
must conform to the doctrine and policy in the SOP of the
higher HQ so that trained personnel reassigned from one
unit to another will have no difficulty or be no less proficient.
As a minimum, the SOP for survey operations should contain
the information and instructions discussed below.
(1) Principal duties of key personnel. This survey SOP
should define the principal duties of key personnel. The
key personnel include the following:
Ž Survey officer of the echelon at which the SOP is
prepared.
Ž Chief surveyor.
Ž Survey team chiefs.
Ž Team members.
Ž Survey officers of subordinate commands, assigned
or attached.
(2) Acceptable methods of survey. The survey SOP
should include the methods of survey acceptable for various
survey tasks. The methods will depend on the type of
instruments available, time available, and status of training
of survey personnel.
(3) Specifications and techniques. The survey SOP
should contain specifications and techniques for fieldwork
and computations. These include such items as the following:
Ž Minimum closures for angles and triangles.
Ž Manner of measuring angles.
Ž Allowable errors.
Ž Station marking techniques.
Ž Recording techniques.
Ž Required degrees of accuracy.
(4) Supply and maintenance information. The survey
SOP should include pertinent information on supply
procedures, stock levels, and maintenance responsibilities
for all survey personnel.
(5) Communications. The survey SOP should include
information pertaining to the use of radios, telephones, visual
signals, and ECCM.
15-9. SURVEY PLANNER’S
GUIDELINES
The guidance below is provided to help the survey planner
prepare a survey plan. Use the guidelines to ensure that none
of the important considerations are omitted.
a. Preparing the Survey Plan.
(1) Enemy forces.
Ž Have all the intelligence data pertaining to the tactical
situation been considered?
Ž HOW will NBC hazards affect survey operations?
(2) Friendly forces. Have all the friendly forces in the
area of operation been identified, and can they provide
logistical support if needed?
(3) Attachments and detachments. Are reinforcing units
needing survey control in the area of operations?
(4) Number of installations.
Ž Have all elements requiring survey control been
identified?
Ž Which installations can provide their own survey
control?
Ž Are there survey requirements from the higher
echelon?
(5) Priority of installations.
Ž What priorities must be established to support the
commander’s guidance and the maneuver forces?
Ž What method of survey should be used to meet the
priority requirements?
(6) Accuracy requirements.
Ž Can the accuracy requirements be met with the
equipment available?
Ž Where can accuracy requirements be relaxed until
accurate data are available?
Ž Does the plan Provide for common control
throughout?
(7) Time requirements.
Ž Can time requirements be met on the basis of time
available, accuracies required, and survey assets
available?
Ž Is additional survey support required, and where is it
available?
15-13
FM 6-2
Ž Dots the plan incorporate time lines that consider
response time for units or systems to meet the
operational times in support of the attack?
(8) Coordination requirements.
Ž Where is the SPCE located?
Ž What survey control is available?
Ž Are trig lists available?
Ž What maps are required?
Ž At what locations is control from higher or lower
echelon required?
(9) Assets (equipment and/or personnel).
Ž Is all survey equipment operational?
Ž Are all survey personnel available?
Ž Can survey equipment be effectively used in existing
terrain and weather?
Ž Does the survey plan provide for continuous
operations?
Ž Does the response time require the survey HQ element
to help the conventional team with survey fieldwork?
(10) Alternatives to the survey plan. Is the survey plan
flexible enough to support maneuver forces under changing
situations?
(11) Command and control.
Ž Is the command and control portion of the survey plan
adequate?
Ž Does the survey plan allow for alternate
communications during intense jamming?
(12) Supply and logistics.
Ž Does the survey section have enough rations for the
first 72 hours of operation?
Ž Does the survey section have enough expendable
supplies (such as hubs, stakes, and batteries) for the
number of positions required?
Ž Do survey operations have to be interrupted for
refueling vehicles, or can the survey vehicles be
resupplied on the move?
15-14
Ž Where are DS maintenance units located for repair or
exchange of equipment?
Ž Does DS maintenance have PADS units or line
replaceable parts available?
Ž Are helicopters available to help the survey effort if
needed?
Ž Does the survey section have its basic load of
ammunition?
(13) Allied requirements.
Ž Does the plan include allied forces?
Ž Is survey support required for any allied units
operating in the-of operations?
Ž What are the survey requirements for the allied units
or systems?
b. Executing the Survey Plan.
(1) Disseminate trig lists, maps, and other pertinent
survey information.
(2) Ensure that survey control is provided—
Ž To prescribed accuracies.
Ž On time.
Ž When needed.
(3) Ensure priorities are met.
(4) Maintain the goal of common control with the higher
echelon.
(5) Maintain continuous communications with all
echelons.
(6) Be prepared to modify the survey plan and execute
changes rapidly.
(7) Inform the commander of the following:
Ž Delay in providing survey control and actions to be
taken to correct this deficiency.
Ž Degraded accuracy caused by lack of time.
Ž Projected time when survey data will be upgraded.
Ž Any deviation from previous guidance.
FM 6-2
APPENDIX A
STANDARDIZED PROCEDURES
The following standardized procedures relevant to survey operations are
denoted in text by a large asterisk (*).
Subject
Location
BUCS
Chapter 12
Field notes
Chapter 4
Station marking
SEDME-MR
Paragraph 5-4b
Duties of survey personnel
Orders of survey accuracy
Paragraph 1-8
Appendix B
Survey forms
Appendix D
Chapter 2, Section ll
A-1
C1, FM 6-2
APPENDIX B
SURVEY STANDARDS AND SPECIFICATIONS
This appendix implements STANAG 2934 and QSTAG 269.
The US government makes nationwide surveys, maps, and charts of various
kinds that must be referenced to national datums. These are necessary
for the conduct of public business, for national defense, and for development
of the country.
B-1. GEODETIC CONTROL SURVEYS
Atmospheric Administration (NOAA), Rockville, Maryland
20852.
a. Geodetic surveys, executed with high precision, are used
to control mapping and charting operations and engineering
projects. The terms geodetic survey and control survey are
almost interchangeable.
B-2. FIELD ARTILLERY
CONTROL SURVEYS
b. Control surveys are of two types-horizontal and vertical.
Horizontal control surveys determine latitudes and longitudes
referenced to a national datum and provide the basis for
rectangular coordinate systems. Horizontal geodetic surveys
are adjusted to the mathematical figure of the earth applicable
to the national datum. Vertical control surveys determine
elevations to a national datum that has been referenced to
tidal measurements. Vertical geodetic surveys are adjusted
with respect to the geoid. These surveys provide permanently
marked and properly described stations.
c. Horizontal control is established by triangulation,
trilateration, and traverse procedures. Vertical control is
established by leveling of a high order of accuracy.
d. The classifications and standards of geodetic control
surveys in the United States are issued by the Federal Geodetic
Control Committee (FGCC) under the authority of the Office
of Management and Budget (OMB). The specifications are
published in a document titled Classification Standards of
Accuracy and General Specifications of Geodetic Control
Surveys and in a supporting document titled Specifications
to Support Classifications, Standards of Accuracy, and
General Specifications of Geodetic Control Surveys. Both
documents are published by and can be obtained from the
National Geodetic Survey Division, National Oceanic and
a. Field artillery control surveys are performed to fourthand fifth-order specifications as described below.
(1) Fourth-order survey is FA survey performed to an
accuracy of 1 unit of error in 3,000 similar units of survey.
It usually is written 1:3,000.
(2) Fourth-order astro azimuth is an FA azimuth
established by astronomical methods, the probable error of
the result of which does not exceed 0.060 mil. The considered
accuracy for FA survey is 0.150 mil.
(3) Fourth-order azimuth is an azimuth of a line used
in the extension of fourth-order survey that, from its point
of origin at a fourth-order astro azimuth line or higher-order
direction, has depreciated in accuracy by a PE value of 0,030
mil per main scheme angle; or it is the azimuth of a line
determined by computation between a fourth-order SCP and
an SCP of equal or higher order. In the latter case, considered
accuracy for FA survey is 0,300 mil.
(4) Fifth-order survey is FA survey performed to an
accuracy of a maximum of 1 unit of error in 1,000 similar
units of survey. It usually is written 1:1,000.
(5) Fifth-order astro azimuth is an FA azimuth established
by astronomical methods, the probable error of the result
of which does not exceed 0.12 mil. The considered accuracy
for FA survey is 0.300 mil.
B-1
C1, FM 6-2
(6) Fifth-order azimuth is an azimuth of a line used in
the extension of fifth-order survey which, from its point of
origin, has depreciated in accuracy by a PE value of 0,09
mil per main scheme angle. A fifth-order azimuth cannot
be obtained by computation between a fifth-order SCP and
an SCP of equal or higher order.
b. The specifications presented in Tables B-1, B-2,
and B-3 are the permissible tolerances allowed to
ensure that the overall standards for fourth- and
fifth-order surveys are achieved. The specifications
apply for determining a 1:500 azimuth. If direction
is not extended from the line established by
observation, the rejection limit can be relaxed to 1.0
mil with a considered accuracy of 1.0 mil, In the
tables, D/R means direct/reverse. In Tables B-1 and
B-2, N represents the number of main scheme angles
used to carry azimuth. In Table B-1, K represents
the total main scheme distance surveyed to the nearest
0.1 kilometer. In Table B-2, K is the sum of the
sides used to compute coordinates. When a computer
or calculator is used, angles and distances may be used
in computations to the nearest 0.001.
Table B-1. Traverse survey specification.
B-2
FM 6-2
Table B-2. Triangulation survey specifications
B-3
FM 6-2
Table B-3. Astronomic azimuth survey specifications
B-4
C1, FM 6-2
APPENDIX C
TRAINING THE FIELD ARTILLERY SURVEYOR, MOS 82C
The purpose of this appendix is to help the survey officer or chief surveyor
conduct a more effective training program. It suggests a program for
training the survey platoon and/or section. There is no single “best” method
of training. What is important is that the training approach used should
be determined in advance and planned in detail.
C-1 . TRAINING PHILOSOPHY
The key to effective performance on the battlefield is a
training program based on planning, conduct (execution),
and evaluation.
a. Planning. Planning is the keystone to interesting,
worthwhile, and effective training. The planning must ensure
that each member of the survey section understands his role
in accomplishing the survey mission of his unit, whether
the unit is a battalion, TAB, or div arty.
b. Conduct. Conduct is the action phase of the training
program. In this phase, the individual surveyor, survey party,
or survey section participates in classroom instruction,
operation of survey instruments, field exercises, and practice
Army training and evaluation programs (ARTEPs).
c. Evaluation. Evaluation is controlled feedback. The
survey officer or chief surveyor must examine the entire
learning process to ensure that the members of the survey
section can successfully accomplish the survey methods,
techniques, and procedures that they have been taught. The
survey officer or chief surveyor conducting the training must
receive controlled feedback after the conduct of an exercise
so that success can be reinforced and mistakes can be
identified and corrected.
C-2. TRAINING THE TRAINER
a. The survey officer is responsible for developing a training
program, for conducting training, and for keeping abreast
of training doctrine. The survey officer uses FMs 25-100
and 25-101 as a guide for planning, conducting, and
evaluating a training program. He uses Soldier Training
Publication (STP) 6-82C 14-SM-TG, and applicable ARTEPs
to determine individual and team qualifications. The trainer’s
guide (STP 6-82C14-SM-TG) lists the critical tasks of MOS
82C, identifies the tasks to be performed at each skill level,
and indicates for each task where the soldier is to be trained.
Used together, these documents become the foundation for
the training program.
b. Supervised on-the-job training (SOJT) may also be used
to train surveyors in the unit. Correspondence subcourses
are excellent for individual and common educational needs,
combined study, and joint discussions and critiques.
Available subcourses and instructions for requesting
correspondence course material are included in DA Pam
351-20.
c. The trainer should ensure that every member of the survey
section has a copy of the soldier’s manual applicable to his
grade. This document outlines performance standards and
gives the soldier a “road map” for progression.
C-3. TRAINING THE SURVEYOR
The trainer must ensure that the individual surveyor is trained
to perform his required tasks. If the individual surveyor
has not attended a service school for his initial survey training,
he must be trained in the unit through various methods,
such as one-on-one instruction, Army correspondence course
lessons, unit school, SOJT, or a combination of these methods.
A unit evaluation of individual knowledge, primarily through
the use of the self-development test (SDT), will determine
if the individual surveyor is knowledgeable in his skill level
and can perform effectively as a member of a survey party.
C-4. TRAINING THE SURVEY
PARTY OR SECTION
When the individual surveyors have attained the desired
level of proficiency, party or section training can be started
with the goal of molding an efficient working team capable
of performing its mission. First, each survey party should
complete miniature field exercises involving position area
survey, target area survey, and connection survey until
the party performs surveys efficiently and with minimum
supervision. The survey parties, operating together as a
C-1
.
—
C1, FM 6-2
survey section, should complete miniature field exercises
until the section can operate efficiently and with minimum
supervision. One type of miniature field exercise is depicted
in Figure C-1. The miniature problem shows each member
of the survey party how his job relates to the party function
as a whole. It facilitates supervision; provides savings
in motor vehicle maintenance, fuel, and time; and requires
no special training area. Full-scale survey operations should
be conducted with an ARTEP as often as necessary to
gain and maintain the required collective proficiency. Figure
C-2 depicts a miniature field exercise for use by the TAB
survey section. Figure C-3 is an example of a miniature
exercise for the div arty survey section.
C-5. SURVEY PARTY OR SECTION
MINIATURE FIELD EXERCISE
a. Before the start of a field exercise, the survey officer
or chief surveyor should draw up the survey plan based
on assumed or real guidance from the commander. If
at all possible, the survey of target area bases, targets,
attached radars, and CEWI sites that normally would be
located in the unit zone of operation should be completed
before the exercise ends.
b. Even though short distances are involved in a miniature
exercise, the SEDME-MR will be exercised adequately.
c. For the purpose of the exercise, true or assumed control
may be used. When assumed control is used, the party
or section should practice conversion to common control.
d. Priority should be given to establishing the essential
survey control in the fastest manner possible on the basis
of guidance from the commander. After this survey is
completed, the party or section could receive additional
training in miniature triangulation schemes.
e. The survey of the battery OLs, attached radars, CEWI
sites, and target area bases must be to the accuracy required
for cannon battalion survey.
C-2
FM 6-2
Figure C-1. Typical FA battalion miniature survey exercise
C-3
FM 6-2
Figure C-2. Typical TAB miniature survey exercise
C-4
FM 6-2
Figure C-3. Typical div arty miniature survey exercise
C-5
FM 6-2
C-6. DESIRABLE TRAINING FACILITIES
The following basic training facilities are desirable for the
conduct of comprehensive training:
Ž TOE of the unit survey section or party.
Ž Beseler Cue/See projectors.
Ž Movie projector (16-mm) with screen.
Ž Classroom.
Ž Outside training area with survey control.
C-6
C1, FM 6-2
*APPENDIX D
REPRODUCIBLE FORMS
This appendix provides a list of the reproducible forms shown at the back
of this book. These forms are not available through publications supply
channels. You may reproduce them locally.
DA Form 5075-R
Artillery Survey Control Point
DA Form 5590-R
Computation of Azimuth and/or Distance From Coordinates (BUCS)
DA Form 5591-R
Computation of Coordinates and Height From Azimuth, Distance, and Vertical Angle (BUCS)
DA Form 5592-R
Computation of Plane Triangle Coordinates and Height From One Side, Three Angles, and Vertical
Angles (BUCS)
DA Form 5593-R
Computation of Coordinates and Height by Three-Point Resection (BUCS)
DA Form 5594-R
Computation of Astronomic Azimuth by Altitude Method Sun (BUCS)
DA Form 5595-R
Computation of Astronomic Azimuth by Altitude Method Star (BUCS)
DA Form 5598-R
Computation of Astronomic Azimuth by Polaris Tabular Method (BUCS)
DA Form 5599-R
Computation—Convergence of True Azimuth to Grid Azimuth (BUCS)
DA Form 5600-R
Computation—Conversion of Geographic Coordinates to UTM Coordinates (BUCS)
DA Form 5601 -R
Computation—Conversion of UTM Coordinates to Geographic Coordinates (BUCS)
DA Form 5604-R
Computation—Zone-to-Zone Transformation— UTM Grid Coordinates and UTM Grid Azimuth (BUCS)
DA Form 7284-R
Computation of Trig Traverse/Subtense (BUCS)
DA Form 7285-R
Computation of Coordinates and Height by Intersection (BUCS)
DA Form 7286-R
Computation of Star Identification (BUCS)
DA Form 7287-R
Computation of Arty Astro (BUCS)
DA Form 7288-R
Computation of Hasty Astro (BUCS)
DA Form 5602-R
Computation of Datum-to-Datum Coordinate Transformation (Program 14—Listed Datums) (BUCS)
DA Form 5603-R
Computation of Datum-to-Datum Coordinate Transformation (Program 15—Gauss-Kruger [GK])
(BUCS)
DA Form 7289-R
Computation of BUCS Datum-to-Datum Coordinate Transformation (Program 16—User-Defined)
(BUCS)
DA Form 7356-R Computation of Azimuth and Distance From Coordinates (FED MSR)
DA Form 7357-R Computation of Coordinates and Height From Azimuth, Distance, and Vertical Angle (FED MSR)
DA Form 7358-R Computation of Plane Triangle Coordinates and Height From One Side, Three Angles, and Vertical
Angle (FED MSR)
DA Form 7359-R Computation of Coordinates and Height by Three-Point Resection (FED MSR)
D-1
C1, FM 6-2
DA Form 7360-R Computation of Astronomic Azimuth by Altitude Method (FED MSR)
DA Form 7361-R Computation of Astronomic Azimuth by the Hasty Astro Method (FED MSR)
DA Form 7362-R Computation of Azimuth and Vertical Angle to Selected Star (Star ID) (FED MSR)
DA Form 7363-R Computation of Astronomic Azimuth by Polaris Tabular Method (FED MSR)
DA Form 7364-R Computation--Convergence of True Azimuth to Grid Azimuth (FED MSR)
DA Form 7365-R Computation of Trig-Traverse (FED MSR)
DA Form 7366-R Computation of Coordinates and Height by Intersection (FED MSR)
DA Form 7367-R Computation of Astronomic Azimuth by the Arty Astro Method (FED MSR)
DA Form 7368-R Computation--Conversion UTM to GEO Coordinate, GEO to UTM Coordinate, Zone-To-Zone
Transformation (FED MSR)
DA Form 7369-R Computation--Datum- To-Datum Coordinate Transformation Listed Datums (FED MSR)
DA Form 7370-R Computation--Datum- To-Datum Coordinate Transformation Gauss Kruger (GK) Datums (FED MSR)
DA Form 7371-R Computation--Datum- To-Datum Coordinate Transformation User-Defined Datums (FED MSR)
D-2
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APPENDIX E
ELLIPSOIDS AND DATUMS
The PADS Core (Version 8), PADS Solid State (Version 4), BUCS Survey (Rev 1),
BUCS DDCT (Rev 0), MADTRAN (Edition 2), MADTRAN (Edition 4), PLGR (Version
04.62), and FED MSR systems contain a data base that stores the relevant constants
and parameters for the ellipsoids listed in Table E-2.
E-1. REFERENCES
a. The following references were used to compile the information
found in this appendix:
(1) DMA TM 8358.1 (September 1990).
(2) DMA TR 8350.2 Second Edition (1 September 1991) with
Insert 1 (9 December 1993).
(3) National Geodetic Survey, Geodetic Glossary (September
1986).
(4) DoD Glossary of Mapping, Charting, and Geodetic Terms
(1991).
(5) MADTRAN, Edition 2 and 4 (DMA program referencing
DMA TR 8350.2 above).
(6) Mercator (DMA program referencing DMA TM 8358.2
(dated September 1989).
(7) TM 08837A-12/1A (28 October 1988) with Change 3 (9
September 1992) PADS.
b. When the information in the references above conflicted, DMA
TR 8350.2 was considered the senior publication.
c. The numbers in front of the references above correspond to the
reference numbers in the tables of this appendix. Reference 8 was
used to determine the PADS ellipsoid code; Reference 4 was used
to determine the BUCS DDCT (Rev 0) code.
E-2. TABLES
a. Ellipsoids.
(1) Table E-1 is a list of all ellipsoids and their parameters as
published in the references above.
(a) This is not a list of all ellipsoids; however, it is the
most complete one-table list of ellipsoids and their parameters
available to artillery surveyors.
(b) The semimajor axis (a), semiminor axis (b), and
flattening (l/f) are listed when available. Semiminor axes not listed
were not available from the references and must be computed by
the user with the formula b = a (l - f).
(2) Table E-2 is a list of the ellipsoids in Table E-1
cross-referenced with current survey applications.
b. Datums.
(1) The datum transformation parameters are listed
corresponding to the ellipsoid to which they are referenced. The
E-1
C1, FM 6-2
transformation parameters are from the local geodetic datum to WGS-84; therefore, a datum table with WGS-84 will not be
published. Also, datum tables for ellipsoids in Table E-1 with no listed datums are not published.
(2) Differences in data published in the above references are explained in the notes section at the end of this appendix.
E-3. WORLD GEODETIC SYSTEM
a. Because of the large amount of mapping, charting, geodetic, gravimetric, and digital products produced by DMA for DoD,
it became apparent that a signle geocentric coordinate system was needed to ensure accuracy and user interface. This system
must support the widest range of applications. A geocentric system provides a basic reference for the mathematical
figure of the earth. It also provides a means for establishing various geodetic datums to an earth-centered, earth-fixed (ECEF)
coordinate system. This system is termed World Geodetic System (WGS).
b. Previously, DoD has adopted three such systems: WGS-60, WGS-66, and WGS-72. With each system proving more
accurate than the last, WGS-72 can still be used for some applications. It does, however, have several shortcomings. For
example, the WGS-72 Earth Gravitational Model and Geoid are obsolete. Also, more accurate datum shifts from local
geodetic datums to a WGS were needed. Several other factors contributed to the need to replace WGS-72. These included
the replacement of NAD 27 with NAD 83 and the development of the Australian Geodetic Datum 84. Also, a large increase
in data and more advanced types of data (satellite ranging for example) were now available. WGS-84 was developed as the
replacement for WGS-72.
c. In determining the WGS-84 ellipsoid and its associated parmeters, the WGS-84 Development Committee closely followed
the procedures used by the International Union of Geodesy and Geophysics (IUGG) who hd lready developed the Geodetic
Reference System 1980 (GRS-80). Four parmeters were used to develop WGS-84: the semimajor axis (a), the earth's
, and the angular velocity
gravitational constant (GM), the normalized second degree zonal gravitational constant
of the earth. All are identical to GRS-80 except that the second degree zonal used is that of the WGS-84 gravitational model
instead of the notation J2 used for GRS-80. As a result of that difference, the ellipsoid parmeters differ slightly between
GRS-80 and WGS-84. These differences are insignificant from a practical application standpoint; therefore, it has been
accepted that GRS-80 and WGS-84 are the same and their associated datums are based on the same ellipsoid. Even so, it
must be understood that WGS-84 is datum within the WGS-84 ellipsoid, and NAD-83 is a datum referenced to the GRS-80
ellipsoid.
d. DMA has designated WGS-84 as the preferred ellipsoid and datum for all mapping, charting, and geodetic products.
Some areas of the world can still be covered by other systems.
Figure E-1. World Geodetic System 1984
E-2
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Table E-1. Ellipsoid parameters
E-3
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Table E-3. Survey system to ellipsoid cross-reference
E-4
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E-4. DATUM TRANSFORMATION TABLES
a. A datum transformation table (Figure E-2) includes the following information:
Ellipsoid name, semimajor axis (a), semiminor axis (b), and flattening (l/f) as listed in Table E-1.
which is the difference between the semimajor axes of the local reference ellipsoid and WGS-84.
which is the difference between the flattenings of the local reference ellipsoid and WGS-84 multiplied by 107.
PADS code as listed in TM 08837A-12/1A. In cases where two or more ellipsoids have the same parameters, the
same PADS code was listed for each even when not listed in the reference. For example, Australian National and
South American 1969 can both use code 8. These codes are for Version 4 PADS. If a PADS code is not listed,
the user-defined option should be used.
Local geodetic datum. The datum name as it appears in DMA TR 8350.2. In cases where a datum has more than
one name, the second name is listed in parentheses.
Country/area. This information is mostly as it appears in DMA TR 8350.2. The only variations from the reference
are listings of states and countries published under mean solutions.
Transformation parameters (shifts in X, Y, and Z axes) as listed in DMA TR 8350.2. These parameters are from the
local datum to WGS-84.
Datum code. The codes in the DATUM CODE column match the programmed datum codes from the AN/PSN-11
(PLGR) Version V04b.2. The datum codes listed in this column that are not a programmed option of the PLGR must
be selected as user-defined. All datum codes published in this table are from DMA TR 8350.2.
DDCT code. This is the datum code from the BUCS DDCT Rev 0.
b. Tables E-3 through E-25 are datum transformation tables. A quick reference to the location of specific tables is on page
E-1.
Figure E-2. Datum transformation table
E-5
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Table E-3. Airy
E-6
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Table E-4. Modified Airy
E-7
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Table E-5. Australian National
E-8
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Table E-6. Bessel 1841
E-9
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Table E-7. Bessel 1841 (Namibia)
E-10
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Table E-8. Clarke 1866
E-11
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Table E-8. Clarke 1866 (Continued)
E-12
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Table E-8. Clarke 1866 (Continued)
E-13
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Table E-9. Clarke 1880
E-14
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Table E-9. Clarke 1880 (Continued)
E-15
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Table E-9. Clarke 1880 (Continued)
E-16
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Table E-9. Clarke 1880 (Continued)
E-17
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Table E-10. Everest 1830
E-18
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Figure E-11. Everest 1948
E-19
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Table E-12. Modified Everest 1948
E-20
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Table E-13. Everest 1956
E-21
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Table E-14. Everest (Pakistan)
E-22
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Table E-15. Modfied Fischer 1960
E-23
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Table E-16. Geodetic Reference System 1980
E-24
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Table E-17. Geodetic Reference System 1980 China
E-25
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Table E-18. Helmert 1906
E-26
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Table E-19. Hough 1960
E-27
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Table E-20. Indonesian 1974
E-28
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Table E-21. International 1924
E-29
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Table E-21. International 1924 (continued)
E-30
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Table E-21. International 1924 (continued)
E-31
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Table E-21. International 1924 (continued)
E-32
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Table E-21. International 1924 (continued)
E-33
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Table E-22. Krassovsky 1940
E-34
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Table E-23. Soviet Geodetic System 1985
E-35
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Table E-24. South American 1969
E-36
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Table E-25. World Geodetic System 1972
E-37
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E-5. NOTES FOR DATUM TABLES
a. Note 1. Any entry reading SEE NOTE ONE in Tables E-3 through E-25 of this appendix are so noted because of
inconsistent listings of datums referenced to the Clarke 1880 ellipsoid. Table E-1 lists five different Clarke 1880 ellipsoids.
DMA has adopted only one. Different countries have adopted different dimensions for the Clarke 1880 ellipsoid. These
differences depend on two things: which of Clarke's original numbers were used ([a, b] or [a, f]) or which foot-to-meter
conversion was used.
(1) In areas referenced to the ARC 1950 datum, the Clarke 1880 dimensions adopted are shown below.
f: 1/293.4663076
b: 6356514.966721
a: 6378249.145326
(2) In areas referenced to Carthage, Merchich, and Voirol datums, the adopted dimensions are shown below.
f: 1/293.46598
b: 6356515.0
a: 6378249.2
(3) The DMA-adopted dimensions are shown below.
f: 1/293.465
b: 6356514.8696
a: 6378249.145
(4) DMA TM 8350.2 with Insert 1 lists datum transformation parameters for local datums referenced to the DMA-adopted
Clarke 1880 and not the dimensions adopted by other countries. Any datum with SEE NOTE ONE in the DDCT CODE
column should be transformed to other datums with the user-defined option.
b. Note 2. WGS-72 is transformed to WGS-84 with a formula that is more accurate than the Abridged Molodensky formulas;
therefore, datum shifts are not necessary. The formulas used are as follows:
whereas:
when:
These formulas are explained in detail in DMA TR 8350.2.
c. Note 3. Herat North Datum was used by the Soviet Union with Krassovsky as the reference ellipsoid in northern Afghanistan.
The US and United Kingdom used Herat North Datum with International as the reference ellipsoid to triangulate in southern
Afghanistan. The connection between these two systems usually differs by 20 to 30 meters. Herat North Datum referenced
to Krassovsky ellipsoid is programmed option in the Gauss-Kruger Grid (Module 15) in the BUCS DDCT Rev 0.
d. Note 4. Potsdam Datum was used with the Gauss-Kruger Grid in eastern Germany and is a programmed option in
Module 15 of the BUCS DDCT Rev 0.
e. Note 5. The IUGG recommended the adoption of the ellipsoid GRS-67 at their 1967 meeting in Lucerne, Switzerland.
The new ellipsoid was adopted for use when a greater degree of accuracy was needed than could be obtained with the
International 1924 ellipsoid. The ellipsoid became part of the Geodetic Reference System of 1967, which was adopted in
1971 by the IUGG meeting in Moscow. This ellipsoid is used in both South America and Australia; however, the name
was changed to South American 1969 and Australian National to more conveniently describe the reference ellipsoid. DMA
TR 8350.2 lists the more convenient names of these ellipsoids.
E-38
FM 6-2
APPENDIX F
GRID ZONE CHART
F-1
F-1 FOLDOUT
F-1 FOLDIN
FM 6-2
APPENDIX G
STAR CARDS
Surveyors should be familiar with the location of stars and the magnitude
of stars. Figure G-2 through G-20 show the constellations recognized by
artillery surveyors. Use the alphabetical index below to locate the
constellation desired. Figure G-1 describes the magnitude of the stars in
the constellations.
CONSTELLATION
SURVEY STARS
MAGNITUDE
FIGURE(S)
Andromeda
Aquila
Aries
Auriga
Bootes
Canis Major
Alpheratz
Altair
Hamal
Capella
Arcturus
Sirius
Adhara
Wezen
Procyon
Canopus
Avior
Misplacidus
Schedar
Caph
Ruchbah
Gamma Cassiopeiae
Rigil Kentaurus
Hadar
Menker
Diphda
Menkar
Alphecca
Gienah
Acrux
Mimosa
Gacrux
Deneb
Eltanin
Achemar
Acamar
Pollux
Castor
Alhena
2.1
0.9
2.2
0.2
G-7, G-8
G-7
G-8
G-5
G-3, G-17
G-6
Canis Minor
Carina
Cassiopeia
Centaurus
Cetus
Corona Borealis (Northern Crown)
Corvus
Crux (Southern Cross)
Cygnus
Draco
Eridanus
Gemini
0.2
-1.6
1.6
2.0
0.5
-0.9
1.7
1.8
2.3
2.4
1.6-2.8
0.1
0.9
2.3
2.2
2.8
2.3
2.8
1.0
1.5
1.6
1.3
2.4
0.6
3.4
1.2
G-6
G-19
G-18
G-20
G-2
G-3
G-9
G-20
G-7
G-18
G-13
G-5
1.6
1.9
G-1
FM 6-2
CONSTELLATION
SURVEY STARS
Great Square
Alpheratz
Enif
Markab
Al Na'ir
Alphard
Beta Hydrus
Regulus
Denebola
Zebeneigenubi
Vega
Nu
Rasalhague
Sabik
Rigel
Betelgause
Bellatrix
Alnilam
Alnitak
Peacock
Enif
Markab
Mirfak
Ankaa
Fomalhaut
Antares
Shaula
Dschubba
Kaus Australis
Nunki
Aldebaran
El Nath
Atria
Alioth
Alkaid
Dubhe
Mizar
Merak
Phecda
Polaris
Kochab
Gamma Velorum
Suhail
Spica
Grus
Hydra
Leo
Libra
Lyra
Octans
Ophiuchus
Orion
Pavo
Pegasus
Perseus
Phoenix
Piscis Austrinus
Scorpius
Sagittarius
Taurus
Triangulum Australe
Ursa Major
Ursa Minor
Vela
Virgo
G-2
MAGNITUDE
2.1
2.5
2.6
2.2
2.2
2.9
1.3
2.2
2.9
0.1
3.7
2.1
2.6
0.3
0.1
1.7
1.7
2.0
2.1
2.5
2.6
1.9
2.4
1.3
1.2
1.7
2.5
1.9
2.1
1.1
1.8
1.9
1.7
1.9
1.9
2.4
2.4
2.5
2.1
2.2
1.9
2.2
1.2
FIGURE(S)
G-10
G-11
G-9, G-14
G-15
G-16
G-7
G-14
G-16
G-8
G-12
G-10
G-8
G-11, G-13
G-11
G-4, G-16
G-4
G-5, G-8
G-14
G-17
G-17, G-18
G-19
G-15
FM 6-2
Figure G-1. Magnitude of stars
Figure G-2. C e t u s
G-3
FM 6-2
Figure G-3. Corona Borealis and Bootes
Figure G-4. Sagittarius and Scorpius
G-4
FM 6-2
Figure G-5. Gemini, Auriga, and Taurus
Figure G-6. Canis Minor, Canis Major, and Orion
G-5
FM 6-2
Figure G-7. Cygnus, Lyra, and Aquila
Figure G-8. Taurus, Perseus, Aries, and Andromeda
G-6
FM 6-2
Figure G-9. Corvus and Hydra
Figure G-10. Andromeda, Great Square, and Pegasus
G-7
FM 6-2
Figure G-11. Phoenix, Piscis Austrinus, and Grus
Figure G-12. Pavo
G-8
FM 6-2
Figure G-13. Eridanus and Phoenix
Figure G-14. Hydra, Octans, and Triangulum Australe
G-9
FM 6-2
Figure G-15. Virgo and Leo
Figure G-16. Ophiuchus, Scorpius, and Libra
G-10
FM 6-2
Figure G-17. Bootes, Ursa Major, and Ursa Minor
Figure G-18. Cassiopeia, Ursa Minor, and Draco
G-11
FM 6-2
Figure G-19. Carina and Vela
Figure G-20. Centaurus and Crux (Southern Cross)
G-12
C1, FM 6-2
APPENDIX H
STANDARDIZATION AGREEMENTS
STANAGs are international agreements to facilitate interallied operations.
Upon ratification by the United States, a STANAG is binding upon US
Army forces (entire/y or with exceptions as noted). This appendix addresses
STANAG 2934 that deals with the required accuracy of survey data and
recording of data for survey control points.
Section I
GENERAL
The following is an extract from STANAG 2934, Section I.
1101. The purpose of this Chapter is to:
a. Standardize the method of expressing the artillery survey accuracy criteria for weapons, target acquisition,
surveillance, and meteorological systems in current use by nations and to establish a common understanding of the
criteria used by nations in order to facilitate mutual survey support.
b. Standardize which data is to be recorded for artillery survey control points and the proforma to be used by NATO
forces.
1102. Participating nations agree to:
a. Use the method of expressing survey accuracy criteria described in Section II.
b. Take note of the criteria set out at Annex A to this Chapter which lists the terminal survey accuracy required by
each nation for weapons, target acquisition, surveillance and meteorological systems.
c. Record the data described in Section III.
d. Use the proforma for artillery survey control points described at Annex B to this Chapter.
1103. An artillery survey control point is defined for use in this chapter as a point at which the coordinates and the
altitude are known and from which the bearings/azimuths to a number of reference points are also known.
H-1
C1, FM 6-2
Section II
STANDARD SURVEY ACCURACY REQUIREMENTS
FOR SURFACE-TO-SURFACE ARTILLERY
The following data are extracted from STANAG 2934, Section II and Annex A.
1104. Survey accuracy requirements are expressed in terms of probable error (PE), circular error probable (CEP), and
standard deviation (SIGMA). Survey parties may express the accuracy of their work in terms of a ratio (for example, 1
in 10000) which is an absolute accuracy.
1105. PE and CEP are derived from the positive standard deviation of the measurement (Sigma -
) as follows:
a.
= Positive standard deviation of the measurement (Sigma).
b. PE= 0.6745
c.CEP=1.1774
d. CEP = 1.7456 PE.
Notes. 1. PE is a value which is exceeded as often as it is not; that is, it has a 50 percent probability of occurrence.
With respect to fixation (position), the PE applies to both the East-West and North-South axis.
2. CEP is the radius of the circle, centered about the true position, such that any measured or calculated position
has a 50 percent probability of lying within that circle.
ARTILLERY SURVEY ACCURACY CRITERIA
H-2
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Section Ill
RECORDING OF DATA FOR
ARTILLERY SURVEY CONTROL POINTS
An extract of STANAG 2934 is shown below.
EXPLANATORY NOTES
AGREEMENT
1. This NATO Standardization Agreement (STANAG) is promulgated by the Chairman MAS under the authority vested
in him by the NATO Military Committee.
2. No departure may be made from the agreement without consultation with the tasking authority. Nations may propose
changes at any time to the tasking authority where they will be processed in the same manner as the original agreement.
3. Ratifying nations have agreed that national orders, manuals, and instructions implementing this STANAG will include
a reference to the STANAG number for the purposes of identification.
DEFINITIONS
4. Ratification is ‘The declaration by which a nation formally accepts the content of this Standardization Agreement.’
5. Implementation is ‘The fulfillment by a nation’s forces concerned of their obligations under this Standardization
Agreement.’
6. Reservation is "The stated qualification by a nation which describes that part of this Standardization Agreement which
it cannot implement or can implement only with limitations."
RATIFICATION, IMPLEMENTATION AND RESERVATIONS
7. Page iii gives details of the state of ratification and implementation of this agreement by the NATO nations. If no
details are shown, it signifies that the nation has not yet notified the tasking authority of its intentions. Page iv (and
subsequent) gives details of reservations and proprietary rights that have been stated.
8. If an amendment of substance of a new edition (other than an editorially amended edition) is promulgated, all
previous ratification, implementation and reservation/restriction details are deleted from pages iii and iv and the
amendment or new edition is processed in the same manner as the original agreement.
Note. The Artillery Survey Control Point Proforma (Amex B to STANAG 2934) has been adapted as a DA form (DA
Form 5075-R) and is discussed in Chapter 14, with the exception that datum and ellipsoid must be included. See the
sample Artillery Survey Control Point Proforma in Annex B and instructions in Section III, 1107d, located in this
appendix, for examples. It is suggested that you still use DA Form 5075-R; just include the datum and ellipsoid data
in the UTM ZONE and UTM SQUARE blocks. (See the back of this book for a reproducible copy of DA Form
5075-R.)
H-3
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RESERVATIONS
DA:
Denmark will not use the proforma (Annex A), but will use existing Danish Trig Lists with text in Danish and
English. In the trig lists all information according to STANAG 2865 is found except:
a. Paragraphs 4b and 5j (direction to orient equipment).
b. Paragraph 5e (accuracy).
c. Paragraph 51 (verification block).
IT:
In the space LOCATION DIAGRAM in Annex A, Italy will also record a vertical sketch with indications of the
altitude of the different collimation plans.
NO:
Norway will use an artillery survey control point proforma with a different layout than that described in Annex A
to STANAG 2865. The Norwegian format will not include information on:
a. UTM square.
b. Accuracy.
c. Longitude/latitude.
d. Bearing/azimuth to aiming points in degrees or grads.
e. Method of determination.
The Norwegian format will include grid bearing/azimuth to only two reference objects from the artillery survey
control point.
ARTILLERY SURVEY CONTROL POINTS
1106. The functions of an artillery survey control point are to:
a. Provide a point from which survey may be opened or closed.
b. Enable users to fix and orient their equipments on the grid applicable to their particular area.
1107. The artillery survey control point proforma (Annex B) will permit quick identification of the control point and
extraction of data without any ambiguity. The following information is required:
a. A control point number and, if desirable, a loclity name.
b. A map series and sheet number.
c. The grid coordinates and the altitude of the control point. (The altitude is that of the ground at the control point
above mean sea level unless otherwise stated.)
d. The type of grid, grid origin, ellipsoid, and datum (normally UTM zone and UTM square).
e. The accuracy of the data. (See Section II.)
f. The specification of the survey methods used:
(1) Horizontal, for exmple, triangulation.
(2) Vertical, for example, altimetry.
(3) Azimuth/orientation, for example, gyroscope.
H-4
C1, FM 6-2
g. A diagram showing the location of the control point in relation to local topographical detail. The diagram is given
in order that the control point may be easily recognized on the ground.
h. The description of the control point; that is, how it is marked on the ground.
j. The grid bearing/azimuths, in mils, to at least four reference objects. Two of these reference objects must be
between 100 and 500 meters of the control point.
k. A description and sketch showing the exact point of lay and the approximate distance from the control point, for
each reference object.
1. A verification block containing:
(1) The unit.
(2) By whom prepared.
(3) By whom checked.
(4) The date.
Notes. 1. There are several ways of writing numbers by hand. The English-speaking nations, for example, use 17.11.
Other nations, for example, use 17,11. Both of these examples can be used but are not to be mixed.
2. When an artillery survey control point is situated near a UTM zone border and two sets of data are available,
separate proforma must be prepared for each UTM zone.
3. The Artillery Survey Control Point Proforma may be printed in national languages, but the format must not be
altered.
H-5
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H-6
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ANNEX C
EVALUATION CHECKLIST
ARTILLERY SURVEY
GENERAL
1. This Chapter agrees the method of expressing artillery survey accuracy criteria for weapons,
target acquisition, surveillance and meteorological systems in current usc by nations. It also
shows the proforma to be used by NATO forces for wording artillery survey control point data
Evaluation opportunities will arise during field training exercises.
EVALUATION PLAN
2.
3.
The information required should be obtained by:
a. Observation of artillery survey teams.
b. Discussion with survey officers/NCOs.
c. Review of national implementing documents.
Questionnaire
4.
of the following equipment types were evaluated? State exact type:
Cannon Artillery
Free Flight Rocket
Surface to Surface Guided Weapon
Mortar Locating Radar
Artillery Locating Radar
Sound Ranging
g. Light Ranging (Flash Spotting)
h. Ground Surveillance Radar
i.
Drone
Which
a.
b.
c.
d.
e.
f.
j.
RPV
k. Meterological Equipment
l.
Ground Laser Locator Designator
5. Was the proforma shown at Annex B (Artillery Survey Control Point) used to record survey
data? State yes or no............ If no, give details:
6. Were all serials on the form completed? State yes or no............
7. Were all the various headings on the form understood by the survey teams? State yes or
no............ If no, give details:
8. Was an Artillery Survey Control Point produced by one nation and used by the survey team
from another nation? State yes or no............If yes, give details:
H-7
C1, FM 6-2
9 . Did the nation using the form require any additional survey information that cannot be shown
on the form? State yes or no............ If yes, give details:
10. Was the survey data shown on the form given to sufficient accuracy to enable the receiving
nation to use it? State yes or no . . . . . . . . . . . .
11.
Was survey carred forward to the weapon/equipment position from the Artillery Survey
Control Point? State yes or no.. . . . . . . . . . .If yes, how far?...............................................
12. If an Artillery Survey Control Point was not used to provide survey information how was
survey initiated? Mark those used:
13. Were gross-error checks on accuracy conducted during the survey process (e.g. compass
checks)? State yes or no . . . . . . . . . . . .
14. Were the accuracies achieved at the weapon/equipment in accordance with the figures
shown at Annex A? State yes or no . . . . . . . . . . . .
15. Do national publications reflect the national accuracies shown at Annex A? State yes or
no . . . . . . . . . . . .
Were there any observations made by exercise participants concerning survey that should be
16.
considered by the Arty WP. State yes or no . . . . . . . . . . . . If YES give:
a. Nation
b. Rank and position of participant
c.
Observation
17. Evaluators own observations:
H-8
C1, FM 6-2
GLOSSARY
AC alternating current
accuracy the degree of conformity with a standard
ADD additional (BUCS)
AE allowable radial error
AFATDS advanced field artillery tactical data system
AFG Afgooye (BUCS)
AFSO aerial fire support observer
AHIP advanced helicopter improvement program
ALB AirLand Battle
altitude the altitude of a celestial body is the arc of its
vertical circle measured from the observer’s horizon to
the body, or it is the vertical angle at the observer’s
position between the horizon and the body
am ante meridiem
amp ampere
angle t the interior angle of the PZS triangle at the
pole. It is measured either eastward or westward between
the observer’s meridian and the hour circle of the
celestial body.
direction of the elevated pole. In astronomic work, the
azimuth angle is the spherical angle at the zenith in
the astronomical triangle composed of the pole, the
zenith, and the star.
azimuth astronomic the angle between the plane of the
observer’s meridian and the plane of the hour circle
containing the observed body, measured in the plane
of the horizon, preferably clockwise from north
azimuth, geodetic the angle between the geodetic
meridian and the tangent to the geodetic line at the
observer, measured in the plane perpendicular to the
ellipsoidal normal of the observer, preferably clockwise
from north. (See survey, geodetic.)
azimuth, grid an azimuth measured from grid north.
(See azimuth, plane and azimuth, projected geodetic.)
azimuth magnetic an azimuth measured from magnetic
north
azimuth, plane the angle measured in a clockwise
direction between grid north and a line on the grid
AOC area of concentration
azimuth, projected geodetic at the point of observation,
the horizontal angle measured clockwise between grid
north and the tangent to the geodetic line to an
observed or designated point. This term must not be
confused with geodetic azimuth.
approx approximately
az mk azimuth mark
AR accuracy ratio (also with BUCS)
AZMK azimuth mark (BUCS)
ARTEP Army training and evaluation program
AZ/MK azimuth to azimuth mark (BUCS)
arty artillery
BO BO in FM 6-300, Tables 12a through e
AS antispooling
B1 B1 in FM 6-300, Tables 12a through e
astro astronomic
B2 B2 in FM 6-300, Tables 12a through e
astro alt astronomic observation (altitude method)
BA=1 side of triangle between Points A and B (BUCS)
az azimuth
azimuth the horizontal angle measured clockwise
between a reference direction and the line to an
observed or designated point
baseline a surveyed line, established with more than
usual care, to which surveys are referred for
coordination and correlation; used as a known length
of a triangle side for computing other triangle sides.
When misinterpretation is not probable, the abbreviation
term base may be used.
azimuth angle the angle less than 180° between the
plane of the celestial meridian and the vertical plane
containing the observed object, reckoned from the
basic control horizontal or vertical control, in which the
locations of the stations have been accurately
coordinated and correlated and forming a framework to
AZ azimuth (BUCS)
Glossary-1
C1, FM 6-2
which other surveys are adjusted. For artillery purposes,
this term can be applied to control points established by
fourth-order accuracy or higher orders of accuracy.
(Practical astronomy assumes that the earth is
stationary and that the celestial bodies rotate about the
earth from east to west on this sphere.)
BC battery center
CEP circular error probable
B/C Point B or C (BUCS)
CEWI combat electronic warfare intelligence
BCS battery computer system
ck check
bde brigade
CK check (BUCS)
bldg building
CM central meridian
blvd boulevard
cmd command
bn battalion
BRP boresight reference point
colatitude the side of the PZS triangle from the celestial
pole to the zenith. The complement of altitude, or 90°
minus the altitude. The term has significance only
when used in connection with altitude measured from
the celestial horizon, when it is synonymous with
zenith distance.
btry battery
C2 command and control
BUCS backup computer system
CMPTD computed (BUCS)
BWI British West Indies
COLT combat observation/lasing team
C Celsius
comm communication
bn SCP battalion survey control point
BOIP basis of issue plan
CA comparative accuracy (BUCS); course acquisition
cont continue
CA=2 side of triangle between Points C and A (BUCS)
CONUS continental United States (also in BUCS)
cav cavalry
CONV conversion (BUCS)
CDU control and display unit (PADS)
CONVG convergence (BUCS)
celestial coordinates the coordinates used to locate a
heavenly body by various systems. The coordinates
used in the field artillery are declination and right
ascension.
COP chief of party
celestial equator the great circle on the celestial
sphere whose plan is perpendicular to the axis of
rotation of
the earth. A great circle is a circle, the plane of which
passes through the center of a sphere.
cot cotangent
celestial horizon that circle on the celestial sphere
formed by the intersection of the celestial sphere and a
plane through the center of the earth and perpendicular
to the zenith-nadir line
CTOC corps tactical operations center
celestial North and South Poles the points at which the
prolonged polar axis of the earth intersects the celestial
sphere
culmination the passage of the celestial body across the
meridian of the observer. Every celestial body will
have two culminations. The passage across the upper
branch of the observer’s meridian is upper culmination
(or upper transit), and the passage across the lower
branch is lower culmination (or lower transit).
celestial sphere an imaginary sphere of indefinitely
large radius whose center is the center of the earth.
Glossary-2
CORR correction (BUCS)
COS cosine (BUCS)
CPT captain
CST central standard time
CTR center (BUCS)
CUCV commercial utility cargo vehicle
C1, FM 6-2
CVG convergence (BUCS)
D direct
measured on a scope. Horizontal distance refers
primarily to taped distances or to distances reduced to
horizontal by computations.
(D) direct (BUCS)
div arty division artillery
DA Department of the Army; Denmark (STANAG)
DMA Defense Mapping Agency
datum a reference element, such as a line or plane, by
reference to which the positions of other elements are
determined. (See datum, horizontal and datum, sea level.)
dN difference in northing
datum, horizontal in plane surveying, the grid system
of reference used for the horizontal control of an area,
defined by the casting and northing of one station in
the area and the azimuth from this selected station to
an adjacent station. This term is differentiated from the
term common grid in that the latter implies a common
datum.
DOS Director of Overseas Survey
datum, sea level a level surface to which heights are
referred. The generally adopted level datum is mean
sea level. For tactical surveys, an arbitrary level datum is
often assumed, as in the case of some local surveys
in which arbitrary level datums are often adopted and
defined in terms of an assumed elevation for some
physical mark (bench mark).
EAC echelon above corps
DoD Department of Defense
DS direct support
DST daylight saving time
DTM datum (AN/PSN-11)
E east; casting (BUCS)
ECCM electronic counter-countermeasures
ECEF earth-centered, earth-fixed
DD.MMYY day, month, year (BUCS)
ecliptic the great circle formed on the celestial sphere
by the plane of the orbit of the earth. If one could
observe the sun and the stars at the same time, he
would see the sun and stars moving slowly across the
sky, with the sun gaining slightly on the stars each
day. Therefore, since for purposes of practical
astronomy the earth is assumed to be stationary, the
ecliptic is assumed to be the path of the sun. This
ecliptic intersects the celestial equator at two points at
an angle of 23.50.
DDCT datum-to-datum coordinate transformations
ECU electronic control unit (SIAGL)
dE difference in casting
eE error in casting
declination the angular distance from the celestial
equator measured along the hour circle of the celestial
body. Declination is positive when the body is north of
the celestial equator and negative when it is south of
the celestial equator. Declination corresponds to
latitude to the earth.
el elevation
DECLN declination (BUCS)
elongation the elongations of a celestial body are two
points in its apparent orbit at which the bearing from
the observer’s meridian is the greatest. A star is said to
be at eastern elongation when its bearing is at its
maximum to the east and at western elongation when
its bearing is at its maximum to the west.
DAYLT daylight (BUCS)
db decibel
DC direct current; daily change (BUCS)
DD.MMSS degrees, minutes, seconds (BUCS)
DEF defined (BUCS)
dH difference in height
dist distance
DIST distance (BUCS)
distance, horizontal the distance measured in a
horizontal plane, as distinguished from a distance
electronic line of sight the characteristics of intervening
terrain that make possible the transmission of a radio
wave between two separated components of the
electronic distance-measuring equipment systems
ElHold elevation hold (AN/PSN-11)
ELPS ellipsoid (BUCS)
Glossary-3
C1, FM 6-2
eN error in northing
GHA Greenwich hour angle
engr engineer
GK Gauss-Kruger
EOL end of orienting line
GMD Greenwich mean date
equinox the equinoxes are the two ponts where the
ecliptic intersects the celestial equator. The point where
the apparent annual path of the sun crosses the
celestial equator from south to north is called the
vernal equinox, or first point of Aries. The other pint
is called the autumnal equinox, where the sun is on the
celestial equator diametrically opposite the vernal
equinox. The equinoctial points move slowly westward
along the ecliptic at a rate of about 50 seconds a year.
As a result, all the fixed stars gradually change their
positions with respect to the equator and the vernal
equinox.
GMT Greenwich mean time
F Fahrenheit; fast (BUCS); flattening (BUCS)
GST Greenwich sidereal time
FA field artillery
gyro gyroscopic
FDC fire direction center
H height
FGCC Federal Geodetic Control Committee
HHB headquarters and headquarters battery
FIST fire support team
HHC headquarters and headquarters company
1 LT first lieutenant
HH.MMSS hours, minutes, seconds
GN grid north
GPS global positioning system
GR.BRIT Great Britain (BUCS)
GRS global reference system
GRU gyroscopic reference unit (SIAGL)
GS general support
GSR general support reinforcing
FLAT flattening
FM frequency modulated; field manual
HI height of instrument
FO forward observer
HMMWV high-mobility multipurpose wheeled vehicle
FOM figure of merit (AN/PSN-11)
FP firing point
FRAGO fragmentary order
FRIG French Frigate Shoals
FS fire support
FSCOORD fire support coordinator
FSE fire support element
FSTK far stake
FWD forward (BUCS)
GAT Greenwich apparent time
GAZ grid azimuth
geo geographic
GEO geographic (BUCS)
Glossary-4
horiz horizontal
horizon the horizon for any place on the surface of the
earth is the great circle formed on the celestial sphere
by the extension of the plane of the observer’s horizon.
In general, the apparent or visible junction of earth and
sky as seen from any specific position.
hour angle the angle at the celestial poles between the
plane of the observer’s meridian and the plane of the
hour circle of the star. Stated simply, the hour angle is
the angle at the pole between the observer’s meridian
and the meridian (hour circle) of the celestial body.
This angle is similar to differences in longitude on the
earth’s surface. It is measured westward from the
observer’s meridian. Generally, the angle is considered
as an arc measured along the celestial equator toward the
west and is expressed in units of time or arc.
hour circle any great circle on the celestial sphere
whose plane is perpendicular to the plane of the
celestial equator
C1, FM 6-2
HQ headquarters
LNG longitude (BUCS)
HRS hours (BUCS)
long longitude
HT height of target; height (BUCS)
HT/T height of target (BUCS)
longitude the angular distance, for a specific spot on the
surface of the earth, from 00 to 180° east or west of
the Greenwich meridian, which is used by most nations
as the prime or initial meridian
hvy heavy
LMT local mean time
hwy highway
LRIP low-rate initial production
Hz hertz
LS launcher site
HZ horizontal (BUCS)
LST local sidereal time (also in BUCS)
ID identification
It light
IEW intelligence and electronic warfare
ltr letter
HT/I height of instrument (BUCS)
IGN Institute Geographic Nationally
mil
IMU inertial measuring unit (PADS)
m meter
inst instrument
M minor (BUCS)
IO instrument operator
MAJ major
IRR infrared reflector
MAJOR semimajor axis (BUCS)
ISTS International Satellite Tracking Station
mal malfunction
IT Italy (STANAG)
IUGG International Union of Geodesy and Geophysics
MAPS modular azimuth positioning system
MEAS measure (BUCS)
km kilometer
met meteorological
KN known (BUCS)
METT-T mission, enemy, terrain and weather, troops
and time available
L left (BUCS); leading (BUCS)
lat latitude
LAT latitude (BUCS)
MHz megahertz
MIN minutes (BUCS)
MINOR semiminor axis (BUCS)
latitude the angular distance, for a specific spot on the
surface of the earth, from 00 to 90° north or south of the
equator
MLRS multiple launch rocket system
LC Lesser Cayman Island
MMSS minutes, seconds (BUCS)
LDG leading edge (BUCS)
MMSSS minutes, seconds to the nearest tenth (BUCS)
LF left (BUCS)
mn mean
LG longitude (BUCS)
MN mean (BUCS)
LHA local hour angle
MOS military occupational specialty
LID light infantry division
MS measuring section
LIN line information number
mm millimeter
MSL mean sea level
Glossary-5
C1, FM 6-2
MSN mission (BUCS)
ORD ordnance (BUCS)
mt mountain
OS orienting station
MTLR moving-target-locating radar
P Point P (BUCS)
MTOE modification tables of organization and
equipment
PADS position and azimuth determining system
M/V manpack/vehicular
N north; northing (BUCS)
NAD North American datum
NBC nuclear, biological, chemical
NICAD nickel-cadmium
no number
PAE position, azimuth, elevation (PADS)
parallax the difference in altitude of a body as seen
from the center of the earth and from a point on the
surface of the earth. There is no apparent parallax of
the fixed stars, but that of the sun and planets is
measurable. Parallax makes the body appear lower than
it actually is; therefore, the correction is added.
PASP platoon area survey point
PDS position determining system
NO Norway (STANAG)
NOAA National Oceanic and atmospheric
Administration
NREF north reference point
NSG north-seeking gyroscope
NSN national stock number
O1 Observer 1 (or Observation Post 1)
O2 Observer 2 (or Observation Post 2)
OBS observation (BUCS)
observer’s meridian the great circle on the celestial
sphere that passes through the celestial poles and the
observer’s zenith-nadir
PE probable error
PFC private first class
PGM program (BUCS)
PLGR precise lightweight GPS receiver
plt platoon
pm post meridiem
PMCS preventive maintenance checks and services
polar distance the algebraic complement of the
declination (90° minus the declination)
pos position
obsr observer
POS position (BUCS)
OCC occupied (BUCS)
PPM parts per million
OL orienting line
OMB Office of Management and Budget
one-position, two-position refers to initial readings on
the circle of the instrument measuring an angle and is
used to determine the degree of refinement in the
performance of angular value determinations with the
theodolite
PPS precise positioning system
prime vertical the vertical circle that is perpendicular to
the plane of the observer’s meridian and intersects the
celestial horizon at the points directly true east and
west of the observer’s meridian
pro forma provided in advance to prescribe form or to
describe items (according to form)
OP observation post
PROV provisional (BUCS)
oper operator
PS power supply (PADS)
OPORD operation order
PT point (BUCS)
OPS observation posts (BUCS)
PTS points (BUCS)
Glossary-6
C1, FM 6-2
P/Y precise (PPS code)
R reverse; right (BUCS); reinforcing
RA right ascension (also in BUCS)
RAM random-access memory
right ascension the right ascension of a celestial body is
the arc on the celestial equator measured from the
vernal equinox eastward to the hour circle of the body.
It is measured in units of time from 0 to 24 hours.
Right ascension corresponds to longitude on earth.
RATELO radiotelephone operator
rotation the turning of a body on its axis. The terminal
points of the axis of the earth are the North and South
Poles. The rotation is from west to east.
rcdr recorder
RP registration point
R3SP rearm, refuel, resupply, and survey point
rd road
RSO reconnaissance and survey officer
RDG reading (BUCS)
RSOP reconnaissance, selection, and occupation of
position
RE radial error of closure; radial error (BUCS)
RECIP reciprocal (BUCS)
recon reconnaissance
recip reciprocal
RECIP reciprocal (BUCS)
REFR refraction (BUCS)
refraction the refraction of a celestial body is the
apparent displacement of the body caused by the
bending of light rays passing through layers of air of
varying density. The celestial body will appear higher
than it really is; therefore, the correction is subtracted.
A simple example of refraction can be seen by placing a
spoon in a glass half full of water.
rejection limit used in FA survey to refer to a
maximum allowable deviation from a mean value of
two or more angular measurements
REQD required (BUCS)
restitution point a point identifiable on a photograph
for which a chart location is known and which is used
to transfer (restitute) other points from the photograph
to the firing chart. The chart locations of these points
may be determined by inspection or by survey.
REV revision (BUCS)
RT right (BUCS)
S south (also in BUCS)
SA selective availability
SCH scheme (BUCS)
SCP survey control point
SDT self-development test
sec second
SEC second (BUCS)
SEDME-MR survey equipment, distance-measuring,
electronic (medium-range)
set (one set, two sets, and so on) used in reference to
astronomic observations of a celestial body. One set
consists of the field data that result from the
observation of a celestial body with the telescope of
the observing instrument, first in the direct position,
then in the reverse position.
SFC sergeant first class
SGS Soviet Geodetic System
SGT sergeant
SHTU simplified hand-held terminal unit
revolution the turning of a body about an exterior point
or axis. The earth revolves about the sun on a
600-million-mile orbit at a speed of about 18.5 miles
per second. Practical astronomy assumes that the earth
is stationary and the celestial bodies move about it
from east to west on the celestial sphere.
SIAGL survey instrument, azimuth gyro, lightweight
RF radio frequency
SIMO simultaneous observation
SIC survey information center
sidereal time time determined by the stars
SIDRL sidereal (BUCS)
Glossary-7
C1, FM 6-2
sin sine
SIN sine (BUCS)
SL slope (BUCS)
SLGR small lightweight GPS receiver
slope distance the straight-line distance between two
points of unequal heights. Normal usage is associated
with electronic distance-measuring equipment. (Do not
use the term slant distance.)
SM soldier’s manual
SO south (BUCS)
SOI signal operation instructions
SOJT supervised on-the-job training
solar time time determined by the sun
solstices the solstices are two points on the ecliptic
midway between the equinoxes. When the ecliptic is
north of the celestial equator, the midpoint is called the
summer solstice and occurs about 21 June. When the
ecliptic is south of the celestial equator, the midpoint is
called the winter solstice and occurs about 21
December. As can easily be seen, the solstices occur
when the sun is at its greatest distance north or south
of the equator.
SOP standing operating procedure
SOR Sorol
SPC specialist
SPCE survey planning and coordination element
SPCO survey planning and coordination officer
sph spheroid
SPS standard positioning system
survey, geodetic survey that takes into consideration the
size and shape of the earth; implies a reference
spheroid that mathematically represents the geoid and
the horizontal and vertical control datums
survey, plane those survey procedures common to field
artillery in which the effect of the curvature of the
earth is almost entirely neglected, and computations of
the relative positions of the stations are made by using
the principles of plane geometry and plane trigonometry
SUSV small-unit support vehicle
SV satellite vehicle (AN/PSN-11)
svy survey (radio net)
SW southwest
SYS system (BUCS)
T telescope (field notebook)
TA target acquisition
TAB target acquisition battery
TACFIRE tactical fire direction system
TAN tangent (BUCS)
TASCP target area survey control point
TA2 true azimuth
TBL table (BUCS)
temp temperature
TG trainer’s guide
tgt target
Thai Thailand (BUCS)
theod theodolite
TM technical manual
SRP/PDS stabilization reference
package/position-determining system
TOC tactical operations center
SSG staff sergeant
TOE tables of organization and equipment
sta station
topo topographic
STA station (BUCS)
TR trailing edge (BUCS)
STP soldier training publication
trig triangulation
TRIG TRAV trig traverse (BUCS)
SUBT subtended or subtense (BUCS)
TRL trailing edge (BUCS)
SURV survey (BUCS)
TS traverse station
Glossary-8
C1, FM 6-2
TTL total traverse length
VHF very high frequency
tundra treeless plain in arctic regions
Viet Vietnam (BUCS)
TZ time zone (BUCS)
w/ with
U/A unadjusted/adjusted
W west (also in BUCS); watch (BUCS)
unk unknown
UNK unknown (BUCS)
WC watch correction
WCS world geodetic system (BUCS)
updt updated(d)
UPS universal polar stenographic
UTM universal transverse mercator (also in BUCS)
WLR weapons-locating radar
WT water tower
V voice (radio net)
XO executive officer
VA vertical angle (also in BUCS)
Y/N yes/no (BUCS)
v DC volts direct current
zenith-nadir the zenith and nadir for any place on the
surface of the earth are two points where an extension
of the observer’s plumb line intersects the celestial
sphere. The zenith is the point directly overhead, and
the nadir is the point directly underneath.
VE vernal equinox
vert vertical
vertical circle any great circle on the celestial sphere
that passes through the observer’s zenith-nadir
Z-VEL zero velocity (PADS)
Glossary-9
C1, FM 6-2
REFERENCES
These are the sources quoted or paraphrased in this
publication.
DA Form 5600-R. Computation-Conversion of
Geographic Coordinates to UTM Coordinates (BUCS).
December 1986.
S T A N A G 2 3 7 3 / Q S T A G 2 6 9 . Survey Accuracy
Requirements for Surface-to-Surface Artillery. 24 January
1992/3 September 1981.
DA Form 5601-R. Computation-Conversion of UTM
Coordinates to Geographic Coordinate (BUCS). December
1986.
STANAG 2865. Recording of Data for Survey Control
Points. 30 December 1991.
DA Form 5602-R. C o m p u t a t i o n — Z o n e - t o - Z o n e
Transformation— UTM Grid Coordinates and UTM Grid
Azimuth (BUCS). December 1986.
SOURCES USED
DA Form 5603-R. Computation of Trig Traverse/Subtense
(BUCS). December 1986.
DA Form 5604-R. Computation of Coordinates and Height
by Intersection (BUCS). December 1986.
DA Form 7287-R. Computation of Datum-to-Datum
Coordinate Transformation (Program 15—Gauss-Kruger
Datums)(BUCS). June 1993.
DOCUMENTS NEEDED
These documents must be made available to the intended
users of this publication.
DA Form 4446. Level, Transit, and General Survey Record
Book. November 1975.
DA Form 5075-R. Artillery Survey Control Point. March
1982.
DA Form 5590-R. Computation of Azimuth and/or Distance
From Coordinates (BUCS). December 1986.
DA Form 5591-R. Computation of Coordinates and Height
From Azimuth, Distance, and Vertical Angle (BUCS).
December 1986.
DA Form 7288-R. Computation of Datum-to-Datum
Coordinate Transformation (Program 15-Gauss-Kruger
[GK]). June 1993.
DA Form 7289-R. Computation of Datum-to-Datum
Coordinate Transformation (Program 16—User-Defined)
(BUCS). June 1993.
DA Form 7284-R. Computation of Star Identification
(BUCS). June 1993.
DA Form 7285-R. Computation of Arty Astro (BUCS). June
1993.
DA Form 7286-R. Computation of Hasty Astro (BUCS).
June 1993.
DA Form 5592-R. Computation of Plane Triangle
Coordinates and Height From One Side, Three Angles, and
Vertical Angles (BUCS). December 1986.
DA Form 7356-R. Computation of Azimuth and Distance
From Coordinates (FED MSR). Sep 96.
DA Form 5593-R. Computation of Coordinates and Height
by Three-Point Resection (BUCS). December 1986.
DA Form 7357-R. Computation of Coordinates and
Height From Azimuth, Distance, and Vertical Angle (FED
MSR). Sep 96.
DA Form 5594-R. Computation of Astronomic Azimuth by
Altitude Method, Sun (BUCS). December 1986.
DA Form 5595-R. Computation of Astronomic Azimuth by
Altitude Method, Star (BUCS). December 1986.
DA Form 7358-R. Computation of Plane Triangle
Coordinates and Height From One Side, Three Angles, and
Vertical Angle (FED MSR). Sep 96.
DA Form 5598-R. Computation of Astronomic Azimuth by
Polaris Tabular Method (BUCS). December 1986.
DA Form 7359-R. Computation of Coordinates and
Height by Three-Point Resection (FED MSR). Sep 96.
DA Form 5599-R. Computation-Convergence of True
Azimuth to Grid Azimuth (BUCS). December 1986.
DA Form 7360-R, Computation of Astronomic Azimuth
by Altitude Method (FED MSR). Sep 96.
References-1
C1, FM 6-2
DA Form 7361-R. Computation of Astronomic Azimuth by
the Hasty Astro Method (FED MSR). Sep 96.
DA Form 7362-R. Computation of Azimuth and Vertical
Angle to Selected Star (Star ID) (FED MSR). Sep 96.
DA Form 7363-R. Computations of Astronomic Azimuth by
Polaris Tabular Method (FED MSR). Sep 96.
DA Form 7364-R. Computation-Convergence of True
Azimuth to Grid Azimuth (FED MSR). Sep 96.
DA Form 7365-R. Computation of Trig Traverse (FED
MSR). Sep 96.
DA Form 7366-R. Computation of Coordinates and Height
by Intersection (FED MSR). Sep 96.
DA Form 7367-R. Computation ofAstronomic Azimuth by
the Arty Astro Method (FED MSR). Sep 96.
DA Form 7368-R. Computation-Conversion UTM to GEO
Coordinate, GEO to UTM Coordinate, Zone-to-Zone
Transformation (FED MSR). Sep 96.
DA Form 7369-R. Computation—Datum-to-Datum
Coordinate Transformation Listed Datums (FED MSR). Sep
96.
DA Form 7370-R. Computation—Datum-to-Datum
Coordinate Transformation Gauss Kruger (GK) Datums (FED
MSR). Sep 96.
DA Form 7371-R. Computation-Datum-to-Datum
Coordinate Transformation User-Defined Datums (FED
MSR). Sep 96.
FM 90-6 (HTF). Mountain Operations. 30 June 1980. FM
90-10 (HTF). Military Operations on Urbanized Terrain
(MOUT) (How to Fight). 15 August 1979.
FM 101-5-1. Operational Terms and Symbols. 21 October
1985.
TM 5-6675-200-14. Operator's, Organizational, Direct
Support and General Support Maintenance Manual for
Directional, 5.9 Inch Long Telescope;
Theodolite:
Detachable Tribrach w/Accessories and Tripod (Wild
Heerbrugg Model T-16-0.2 Mil) . . . . 31 May 1973.
TM 5-6675-205-20P. Organizational Maintenance Repair
Parts and Special Tool Lists: Theodolite: Directional;
0.002 Mil Graduation: 5.9-Inch Long Telescope, Detachable
Tribrach; w/Accessories and Tripod (Wild Heerbrugg Models
T-2-56-M-MIL). . . (Model
T-2-56-C-MIL)... (Model
T-2-56-M-MIL, Reference and T-2-56-C-MIL, Reference) . . . .
10 December 1969.
TM 5-6675-233-20P. Organizational Maintenance Repair
Parts and Special Tools List: Theodolite: Directional;
0.002 Mil Graduation; 5.9-Inch Long Telescope; Detachable
Tribrach w/Accessories and Tripod (Wild Heerbrugg Models
T2-63 MIL)... (Model T2-67 MIL)...and (Model T2-66-C
MIL) . . . . 25 June 1970.
TM 5-6675-243-15. Operator ‘s, Organizational, Direct
Support, Genera! Support, and Depot Maintenance Manual
(Including Repair Parts List): Light, Target, Surveying u/w
Range Pole, Self-Iluminating w/Carrying Case (Military
Design) . . . . 3 March 1966.
TM 5-6675-250-10. Operator’s and Organizational
Maintenance Manual: Survey Instrument, Azimuth, Gyro,
Lightweight Model AG-8, Type 1 ....30 June 1986.
FM 21-26. Map Reading and Land Navigation. 30 September
1987.
TM 5-6675-270-15. Operator's, Organizational, Direct and
General Support and Depot Maintenance Manual:
Theodolite: Directional; 0.2 Mil Graduation; 5.9 In. Long
Telescope w/Accessories (Wild Heerbrugg Models) (Mode!
T16-MIL66, Type II)..., (Model T16-MIL-68, Type II.. and
Theodolite, Directional, 1 Min Graduation; 5.9 Inch Long
Telescope w/Accessories (Wild Heerbrugg Model T16-68
DEG Type I) . . . . 12 March 1970.
FM 21-31. Topographic Symbols. 19 June 1961.
TM5-6675-296-14. Operator‘s, Organizational, Direct Support
FM 25-100. Training the Force. 15 November 1988.
and General Support Maintenance Manual for Theodolite,
Directional: 0.002 Mil Graduation, 5.9 Inch Long Telescope,
Detachable Tribrach w/Accewories and Tripod (Wild Heerbrugg
Models T2-56-C-MIL)..., (Model T2-56-M-MIL)..., (Model
T2-63-MIL)..., (Model T2-66-C-MIL)..,, (Model T2-68-MIL)...;
Theodolite, Directional (Reference) (Wild Heerbrugg Models
T2-56-C-MIL, T2-56-M-MIL, T2-63-MIL, T2-66-C-MIL,
T2-67MIL and T2-68MIL) . . . . 28 June 1977.
FM 6-50. Tactics, Techniques, and Procedures for the Field
ArtilIery Cannon Battery. 20 November 1992.
FM 6-300. Army Ephemeris, 1993-1997. 23 July 1992.
FM 25-101. Battle Focused Training. 30 September 1990.
FM 31-70. Basic Cold Weather Manual. 12 April 1968.
FM 31-71. Northern Operations. 21 June 1971.
FM 90-5 (HTF). Jungle Operations. 16 August 1982.
References-2
C1, FM 6-2
TM 5-6675-302-14&P. Operator’s Organizational, Direct
Support and General Support Maintenance Manual Including
Repair Parts and Special Tools List for Target Set, Azimuth
Laying (Wild Heerbrugg Model 242406)...and (Model
USATS-79) . . . . 25 February 1982.
TM 5-6675-304-12. Operator’s and Organizational
Maintenance Manual for Survey Electronic Distance
Measuring Equipment, Infrared, Model DM-60(A4-1)....31
July 1980.
AR 115-11. Army Topography. 1 March 1980.
AR 310-25. Dictionary of United States Army Terms. 15
October 1983.
AR 310-50. Authorized Abbreviations and Brevity Codes.
15 November 1985.
AR 600-20. Army Command Policy. 30 March 1988.
Classification, Standards of Accuracy and General Specifications
of Geodetic Control Surveys
TM 5-6675-308-12. Operator’s and Organizational
Maintenance Manual for Position and Azimuth Determining
System,
AN/USQ- 70,
Part
No.
880500-1...(TM
08837A-12/1A) . . . . 28 October 1988.
*TM 5-6675-330-10. Operator Manual North-Seeking
Gyroscope (NSN 6675-01-391-9079). 10 June 1994.
DA Form 2028. Recommended Changes to Publications and
Blank Forms. February 1974.
DA Pam 351-20. Army Correspondence Course Program
Catalog. 1 April 1991.
TM 9-1220-242-12&P. Operator’s and Organizational
Maintenance Manual (Including Repair Parts and Special
Tools List for Computer Set, Field Artillery, General.. and
Computer Set, Field Artillery, Missile . . . . 25 May 1983.
DMA Technical Manual (TM) 8358.1, Datums, Ellipsoids,
Grid and Grid Reference Systems, Preliminary Edition,
Undated, DMA Stock No. DMA TM 8358.1 TEXT (Replaces
Department of the Army TM 5-241-1 titled Grids and Grid
References.)
TM 9-1290-262-10. Operator’s Manual for Aiming Circle,
M2 W/E... and M2A2 W/E . . . . 15 April 1981.
DMA Technical Report (TR) 8350.2 Department of Defense
World Geodetic System 1984. September 1987.
TM 9-6140-200-14. Operator’s, Unit, Intermediate Direct
Support and Intermediate General Support Maintenance
Manual for Lead-Acid Storage Batteries; 4HN, 24
Volt... MS75047-1; 2HN, 12 Volt... MS35000-1; 6TN, 12
Volt...MS35000-3; 6TL, 12 Volt... MS52149-1 . . . . 13 July 1989.
Order DMA TM 8358.1 from:
TM 9-7000-200-13&P. Operator’s, Organizational, and
Direct Support Maintenance Manual Including Repair Parts
and Special Tools List for Computer System, Backup,
General... and Special . . . . 3 June 1985.
TM 11-5825-291-13, Satellite Signals Navigation System
AN/PSN-11. 1 June 1994.
Requests for DMA TR 8350.2 should be sent to:
TM 11-7025-300-10. Opeator's Mnual Forward Entry
Device (FED) Mer/Survey (MSR) (Digital Data Set,
AN/PSG-7 Software) (NSN 7035-01-342-4837) (EIC: N/A),
1 November 1993.
TM 11-7025-311-12&P. Operator’s Unit Maintenance
Manual Including Repair Parts and Special Tools List for
Printer, Automatic Data Processing Part Number 50786
(NSN 7025-01-381-0760) (EIC: N/A). 1 February 1994.
FM 5-105. Topographic Operations. 9 September 1987.
READINGS RECOMMENDED
Defense Mapping Agency Combat Support Center
ATTN: DDCP
Washington, DC 20315-0020
Defense Mapping Agency
ATTN: PR
Building 56
United States Naval Observatory
Washington, DC 20305-3000
FM 5-146. Engineer Topographic Units. September 1979.
FM 6-20. Fire Support in the AirLand Battle. 17 May 1988.
FM 6-30. Tactics, Techniques, and Procedures for Observed
Fire. 16 July 1991.
FM 6-40. Field Artillery Manual Cannon Gunnery. 27
December 1988.
These readings contain relevant supplemental information.
FM 6-50. Tactics, Techniques, and Procedures for the Field
Artillery Cannon Battery. 20 November 1990.
AR 70-38. Research, Development, Test, and Evaluation of
Material for Extreme Climatic Conditions. 1 August 1979.
FM 6-121. Tactics, Techniques, and Procedures for Field
Artillery Target Acquisition. 25 September 1990.
References-3
C1, FM 6-2
HP71B Owner’s Manual.
HP71B Reference Manual.
Specifications to Support Classifications, Standards of
Accuracy, and General Specification of Geodetic Control
Surveys
HP71B Interface Owner’s Manual.
HP2225B Reference Manual.
STANAG 2210. Trig Lists (Lists of Geodetic Data). 9 June
1969.
STANAG 2211. Geodetic Datums, Spheroids, Grids, and
Grid References, 15 July 1991.
STP 6-82C 14-SM-TG. Soldier’s Manual and Trainer’s
Guide: 82C, Field Artillery Surveyor (Skill Levels 1/2/3/4).
17 July 1991.
TM 5-232. Elements of Surveying. 1 June 1971.
References-4
C1, FM 6-2
INDEX
This index is organized alphabetically by topic and subtopic. Topics and subtopics are identified by page number.
Accessories
distance-measuring equipment (SEDME-MR), 2-12
north-seeking gyroscope, 8-13
surveying instrument, azimuth gyro, 8-1
taping, 2-1
theodolite, T16, 3-1
theodolite, T16-84, 3-1
theodolite, T2, 3-17
Accidental errors, 2-9
Accuracy
astronomic observation, 7-39, B-1, H-2
comparative, of taped distance, 2-9
field artillery target acquisition battery and detachment
survey, 14-14
Angle
azimuth, 7-7
Angles
determining with theodolite. See Theodolite, T16,
T16-84 and Theodolite T2.
distance, 6-4
horizontal, 3-6
vertical, 3-8
Arctic surveying, 14-20
Assumed data, 14-2
Astronomic observation
accuracy, B-1, 7-39
astronomic triangle, 7-5
azimuth angle (zenith angle), 7-7
intersection, 6-19
celestial equator, 7-4
simultaneous observation, 7-51
celestial sphere, 7-2
traverse, 5-1
coaltitude, 7-6
triangulation, 6-7
colatitude, 7-7
trig-traverse, 5-25
elements, 7-4
Adjustment
hour angle (angle t), 7-7
theodolite, T16, 3-12
interior angles, 7-7
theodolite, T16-84, 3-15
parallactic angle, 7-7
theodolite, T2, 3-21
solution, 7-7
traverse (azimuth, coordinates, and height), 5-33
Alignment, tape, 2-3
computations
altitude method, 7-33
Index-1
C1, FM 6-2
arty astro method (sun), 7-36
apparent motion of sun, 7-9
arty astro method (star), 7-36
basis of, 7-8
Polaris tabular, 7-39
conversion
earth, 7-1
LMT to GMT, 7-12
field requirements, 7-14
LMT to Greenwich apparent time, 7-12
field data, 7-14
LMT to LHA, 7-12
local hour angle, 7-12
relation to longitude, 7-9
locating stars, 7-24
sidereal, 7-13
methods of determining azimuth, 7-13
solar day, 7-9
altitude, 7-13, 7-33
solar year, 7-9
arty astro, 7-14, 7-39
universal, 7-11
observing procedures, 7-16
zones, 7-10
nomograph, simultaneous observation, 7-50
Polaris tabular, 7-44
pointing techniques, 7-15
polar distance, 7-5
recording and meaning data 7-16
Azimuth
adjustment, 5-33
computed from coordinates, 5-16
conversion, 14-4
determined by astronomic observation. See
right ascension, 7-4
Astronomic observation.
selection and identification of stars, 7-22
grid, 8-10
selection of methods of observation, 7-57
transformation, 11-6
sidereal time, 7-13
true, 8-10
simultaneous, 7-48
solution of PZS triangle (Southern Hemisphere), 7-58
Azimuth gyro. See Survey instrument, azimuth gyro,
lightweight.
spherical coordinates, 7-2
techniques of observing, 7-13
Base
temperature, 7-15
target area, 14-7
time
triangulation, 6-2
angle t, 7-8
Index-2
trig traverse, 5-26
C1, FM 6-2
Battalion and battery survey, field artillery
assumed data, 14-2
astronomic observation, 7-1
connection survey, 14-7
converting to higher-echelon grid, 14-2
position area survey, 14-4
survey control
methods, 14-2
points, 14-5
target area
survey, 14-7
Coast and geodetic survey publications. See National
Oceanic and Atmospheric Administration Publications.
Collimation adjustments
theodolite, T16, 3-15
theodolite, T16-84, 3-15
theodolite, T2, 3-23
Common grid, 14-1
Comparative accuracy of taped distances, 2-9
Computations
astronomic observations, 7-33, 7-39, 7-45, 10-9, 10-19,
10-25
coordinates, 5-8, 10-5
Bearing, 5-12
distance, 5-8, 10-5
Blunders, 2-9
intersection, 6-12, 10-19
Breaking tape, 2-6
resection, 6-20, 10-9
Computers
Celestial
bodies, 7-1
equator, 7-4
meridian, 7-3
simultaneous observation, 7-48
sphere, 7-2
accessories, 10-1, 12-1
keyboard entries, 10-1, 12-2
keyboard computations, 10-3, 12-7
maintenance, 12-12
Computer (survey party), 1-10, 5-6
Connection survey, 14-7
triangle, 7-5
Chain of triangles, 6-5
Chart, star. See Star chart.
Chief of party, 1-10
Control
point, survey, 14-5
starting, 5-2
Clamping handle, 2-2
Convergence, 8-10
Closed traverse, 5-3
Conversion
Closure, triangle, 6-8
coordinates. See also Coordinates, conversion.
Index-3
C1, FM 6-2
geographic to grid, 11-1
grid to geographic, 11-4
setting up, 2-14
Division artillery survey
survey control, 14-2
mission, 14-13
to higher-echelon control, 14-2
officer, duties, 14-13
true azimuth to grid azimuth, 8-10
planning, 15-1, 15-7
Coordinates
adjustments, 5-34
conversion, 14-2
geographic, 11-1
transformation, 11-6
Data, assumed, 5-3, 14-2
Data, starting, 5-2
Declination
celestial body, 7-4
magnetic disturbance, 14-6
station, 9-5, 14-6
requirements, 15-1
survey control, 14-13
Duties of survey personnel, 1-10
Execution of survey order, 15-10
Factors affecting survey planning, 15-8
Field artillery (FA)
battalion and battery. See Battalion and battery survey.
target acquisition battery. See Target acquisition
battery survey.
Field notes
astronomic observation, 4-12, 4-10, 4-11
Desert survey, 14-21
notebook, 4-1
Directional traverse, 5-4
PADS, 4-4
Distance
resection, 4-9
angles, 6-4
traverse, 4-6, 4-7
computed coordinates, 5-13
triangulation, 4-7, 4-8
taped. See Taping.
Distance-measuring equipment
accessories, 2-12
Fifth order, B-1
Figures, strength, 6-6
Forms, DA
care and maintenance, 2-16
DA Form 5075-R, 14-17 and 14-18
controls, 2-14
DA Form 5590-R, 5-11
description, 2-12
DA Form 5591-R, 5-18 and 5-21
operation, 2-14
DA Form 5592-R, 6-9 through 6-11
lndex-4
C1, FM 6-2
DA Form 5593-R, 6-21
DA Form 7368-R, 10-30
DA Form 5594-R, 7-35
DA Form 7369-R, 10-31
DA Form 5595-R, 7-38
DA Form 7370-R, 10-34
DA Form 5598-R, 7-47
DA Form 7371-R, 10-34
DA Form 5599-R, 8-12
Forward station, 5-1
DA Form 5600-R, 11-3
Fourth order, 5-24, B-1
DA Form 5601-R, 11-5
Geographic coordinates, 11-1
DA Form 5602-R, 11-8
Global positioning system, 13-1
DA Form 5603-R, 5-28
Grid
DA Form 5604-R, 6-17
azimuth, 5-8
DA Form 7287-R, 11-17 through 11-20
common, 14-1
DA Form 7288-R, 11-25 through 11-28
Ground reconnaissance, 6-2
DA Form 7289-R, 11-32 through 11-34
DA Form 7285-R, 7-42, 7-43
Gyro azimuth survey instrument. See Survey
instrument azimuth gyro, lightweight or
north-seeking gyroscope
DA Form 7286-R, 7-55, 7-56
Height
DA Form 7284-R, 7-30, 7-31
DA Form 7356-R, 10-6
adjustment, 5-34
DA Form 7357-R, 10-7
difference in (dH), 5-14
DA Form 7358-R, 10-10
error of closure of, 5-24
DA Form 7359-R, 10-13
of instrument (HI), 5-14
DA Form 7360-R, 10-14
trigonometric
DA Form 7361-R, 10-17
intersection, 6-15
DA Form 7362-R, 10-20
resection, 6-20
DA Form 7363-R, 10-21
traverse, 5-14
DA Form 7364-R, 10-22
triangulation, 6-5
DA Form 7365-R, 10-23
DA Form 7366-R, 10-24
DA Form 7367-R, 10-26
Horizontal angles
determining with theodolite. See Theodolite, T16,
T16-84 and Theodolite T2.
Index-5
C1, FM 6-2
Horizontal scales. See Scales, reading.
Mission, survey, 1-1
Horizontal taping, 2-1
Multiple launch rocket system (MLRS), 14-8
Initial circle settings, 3-6
Nadir, 3-8
theodolite, 3-19
Instrument
height, 5-14
operator, 1-10, 5-6
Intersection
Night
lights used with range pole, 5-7
taping, 2-10
Northing, difference in (dN), 5-13
North-seeking gyroscope
accuracy, 6-19
accuracy, 8-13
computations, 6-12
components, 8-13
definition, 6-15
E-2 additive constant, 8-15
limitations, 6-15
maintenance, 8-16
techniques, 6-15
setup, 8-15
Jungle survey, 14-21
survey application, 8-15
Latitude, parallels, 7-2
Notebook. See Field notes.
Law of sines, 6-24
Notes, field. See Field notes.
Legs, traverse, 5-1
Observation
Level
for range pole, 5-4
plate. See Plate levels.
astronomic. See Astronomic observation.
post(s), 14-7
target area
azimuth mark, 14-7
Leveling
Occupied station, 5-1
the theodolites, 3-3, 3-18
Open traverse, 5-3
Lights used on range poles, 5-7
Operator, instrument, 1-10, 5-6
List, trig, 14-2
Optical plumb, 3-4
Longitude, meridians, 7-2
Orienting
Mean solar time, 7-9
angle, 14-5
Methods, survey, use, 15-9
line, 14-5
Missile battalion survey, 14-8
point, radar, 14-5
Index-6
C1, FM 6-2
station, 14-5
Ratio, accuracy, traverse, 5-22
Paladin, 14-8
Rear station, 5-1
Parallax, 3-5, 7-32
Reciprocal measurements of vertical angles, 5-22
Party, traverse, 5-5
Reconnaissance, 6-2
Patriot missile, 14-10
Recorder, 1-10, 5-7. See also Recording.
Pins, taping. See Taping, pins.
Reduced-strength party, 5-7
Planning, survey. See Survey planning.
Reference stake, 5-4
Plate levels
Refraction, 7-18, 7-32
theodolite, T16, 3-13
Relationship, azimuth and bearing, 5-12
theodolite, T16-84, 3-16
Repair, tape, 2-11
theodolite, T2, 3-21
Resection
Plumb bob
used in taping, 2-2, 2-5
used with theodolite, 3-1
Pointings, 3-20
Pole, celestial north and south, 7-2
Position
area survey, 14-4
taken with theodolite. See Theodolite, T16, T16-84 and
Theodolite, T2.
Position and azimuth determining system (PADS)
AN/USQ-70, 9-1
Prescribed accuracy. See Accuracy.
PZS triangle, 7-5
Radar
surveying for, 14-5
computations, 6-20
definition, 6-20
three-point, 6-20
Restrictions on survey operations, 15-8
Right ascension (RA), 7-4
Satellite signals navigation set AN/PSN-11, 13-1
Scales, reading
theodolite, T16, 3-5
theodolite, T16-84, 3-5
theodolite, T2, 3-18
Schemes of triangles, 6-5
Selection of methods of astronomic observation, 7-57
Sidereal time, 7-13
Signs of dE and dN, 5-14
Simultaneous observation, 7-48
Radio time signals, 7-39
accuracy, 7-51
Range poles, 5-4
procedures, 7-48
Index-7
C1, FM 6-2
Sines, law of, 6-24
mission, 1-1
Single triangles, chain, 6-5
orders, 15-11
Sketch, 4-3
planning, 1-1, 15-1
Sliding the grid, 14-2
Solar time, 7-9
steps in survey planning, 15-10
Survey instrument, azimuth gyro, lightweight
Spherical triangle, 7-5
accuracy, 8-1
Stake, reference, 5-4
components, 8-1
Standardization Agreements
description, 8-1
STANAG 2934, 14-19, H-1
maintenance, 8-9
Standing operating procedure (SOP), 15-12
Star
chart, 7-23
identification, 7-20
operation, 8-7
setting up, 8-2
taking down, 8-8
Swinging the grid, 14-4
Systematic errors, 2-9
Starting
Tape
control, traverse, 5-2
alignment, 2-3
data, traverse, 5-2
breaking, 2-6
Station
lengths, measuring, 2-5 through 2-7
forward. See Forward station.
maintenance, 2-10
occupied. See Occupied station.
repair, 2-11
orienting, 14-5
Tapeman, 2-1
rear. See Rear station.
Tapes
traverse, 5-4
description, 2-1
Survey planning and coordination element (SPCE),
14-14
Taping
Strength of figures, 6-6
accessories, 2-1
Survey
comparative accuracy, 2-9
control points, 14-5
errors, 2-9
methods, 15-9
measuring distances in excess of 10 tape lengths, 2-6
Index-8
C1, FM 6-2
night, 2-10
determining vertical angles, 3-21
notes, 2-2
horizontal circle readings, 3-19
partial tape lengths, 2-7
initial circle settings, 3-19
pins, 2-2, 2-5
measuring horizontal angles, 3-20
techniques and specifications, 2-9
pointings, 3-20
Target acquisition battery (TAB) survey, fieId artillery
survey control points, 14-5
survey planning and coordination element, 14-14
preparing for use, 3-18
Three-point resection. See Resection.
Target set, survey, 5-5
Time, 7-8 through -13. See also Astronomic
observation, time.
Temperature, astronomic observations, 7-15
Training the field artillery surveyor, C-1
Theodolite, T16, T16-84
Transformation, azimuth and coordinates, 11-6
accessories, 3-1
adjustments, 3-12
Traverse
accuracy, 5-23, B-2
adjustments for parallax, 3-5
radial error, 5-22
care and cleaning, 3-10
ratio, 5-22
computing horizontal and vertical angles, 3-9
adjustment, 5-33 through 5-35
description, 3-1
azimuth and bearing relationship, 5-12
horizontal angles, measuring, 3-6
azimuth error, closing, 5-23
reading and setting horizontal and vertical circles, 3-5
computations, 5-16
repair, 3-10
definition, 5-1
setting up, 3-1
determination of dH, 5-14
taking down, 3-4
directional, 5-4
vertical angles, determining, 3-8
distance measurement
Theodolite, T2
accessories, 3-18
with SEDME-MR, 2-12
tape. See also Taping.
adjusting for parallax, 3-18
extending azimuth, 5-8
adjustments, 3-21
field notes, 5-7
description, 3-17
fieldwork, 5-1
Index-9
C1, FM 6-2
isolation of error, 5-29
resection, three-point
night, 5-7
limitations, 6-15
organization of parties, 5-5
use, 6-20
reciprocal measurement of vertical angles, 5-22
reconnaissance, 6-2
specifications, 5-23
schemes, 6-5
starting control, 5-2
single triangles, 6-5
stations, 5-4
single chain of triangles
techniques, 5-23
checks, 6-5
trigonometry of, 5-13
description, 6-5
types, 5-3
solution, 6-5
Triangle, astronomic (PZS), 7-5
strength of figures, 6-6
Triangle, error of closure, 6-10, B-3
reconnaissance, 6-2
Triangles, chain of, 6-5 through 6-7
specifications, 6-3
Triangulation
vertical angles, 6-4
accuracy, B-3
Trig list, 14-2
application, 6-1
Trig traverse
base measurement, 6-3
angles, 5-26
computations, 6-3
base accuracy, 5-26
definition, 6-1
length computations, 5-26
distance angles
single triangle, 6-4
chain of triangles, 6-5 through 6-7
method, 5-25
targets, 5-26
Tripod, ranging pole, 5-4
error of closure, 6-8
True azimuth (astronomic), 7-1
field notes, 6-3
intersection
Vernal equinox, 7-4
computations, 6-16
limitations, 6-15
parties, 6-2
Index-10
Vertical angle correction (VAC), 9-5
Vertical angles
C1, FM 6-2
determining, with theodolite. See Theodolite, T16,
T16-84 and Theodolite, T2.
reciprocal measuring, 5-22, 6-4
Vertical scales. See Scales, reading.
Weapon position, field artillery, 14-4, 4-8, 14-10
Weather, effects of, on survey, 15-8
Zenith, 7-5
Zone-to-zone transformation, 11-6
Index-11
23
FM 6-2
SEPTEMBER 1993
By Order of the Secretary of the Army:
GORDON R. SULLIVAN
General, United States Army
Chief of Staff
Official:
MlLTON H. HAMILTON
Administrative Assistant to the
Secretary of the Army
04922
DISTRIBUTION:
To be distributed in accordance
Active Army, USAR, and ARNG:
with DA Form 12-11E, requirements for FM 6-2, Tactics,
Techniques, and Procedures for Field Artillery Survey
(Qty rqr block no. 0765).
U.S. GOVERNMENT PRINTING OFFICE: 1993 728-027/80076
PIN: 021506-000